text: // vim: ts=4 sts=4 sw=4 expandtab
  // -- kriskowal Kris Kowal Copyright (C) 2009-2011 MIT License
  // -- tlrobinson Tom Robinson Copyright (C) 2009-2010 MIT License (Narwhal Project)
  // -- dantman Daniel Friesen Copyright (C) 2010 XXX TODO License or CLA
  // -- fschaefer Florian Schäfer Copyright (C) 2010 MIT License
  // -- Gozala Irakli Gozalishvili Copyright (C) 2010 MIT License
  // -- kitcambridge Kit Cambridge Copyright (C) 2011 MIT License
  // -- kossnocorp Sasha Koss XXX TODO License or CLA
  // -- bryanforbes Bryan Forbes XXX TODO License or CLA
  // -- killdream Quildreen Motta Copyright (C) 2011 MIT Licence
  // -- michaelficarra Michael Ficarra Copyright (C) 2011 3-clause BSD License
  // -- sharkbrainguy Gerard Paapu Copyright (C) 2011 MIT License
  // -- bbqsrc Brendan Molloy (C) 2011 Creative Commons Zero (public domain)
  // -- iwyg XXX TODO License or CLA
  // -- DomenicDenicola Domenic Denicola Copyright (C) 2011 MIT License
  // -- xavierm02 Montillet Xavier XXX TODO License or CLA
  // -- Raynos Raynos XXX TODO License or CLA
  // -- samsonjs Sami Samhuri Copyright (C) 2010 MIT License
  // -- rwldrn Rick Waldron Copyright (C) 2011 MIT License
  // -- lexer Alexey Zakharov XXX TODO License or CLA
  
  /*!
      Copyright (c) 2009, 280 North Inc. http://280north.com/
      MIT License. http://github.com/280north/narwhal/blob/master/README.md
  */
  
  define(function(require, exports, module) {
  
  /*
   * Brings an environment as close to ECMAScript 5 compliance
   * as is possible with the facilities of erstwhile engines.
   *
   * Annotated ES5: http://es5.github.com/ (specific links below)
   * ES5 Spec: http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf
   *
   * @module
   */
  
  /*whatsupdoc*/
  
  //
  // Function
  // ========
  //
  
  // ES-5 15.3.4.5
  // http://es5.github.com/#x15.3.4.5
  
  if (!Function.prototype.bind) {
      Function.prototype.bind = function bind(that) { // .length is 1
          // 1. Let Target be the this value.
          var target = this;
          // 2. If IsCallable(Target) is false, throw a TypeError exception.
          if (typeof target != "function")
              throw new TypeError(); // TODO message
          // 3. Let A be a new (possibly empty) internal list of all of the
          //   argument values provided after thisArg (arg1, arg2 etc), in order.
          // XXX slicedArgs will stand in for "A" if used
          var args = slice.call(arguments, 1); // for normal call
          // 4. Let F be a new native ECMAScript object.
          // 11. Set the [[Prototype]] internal property of F to the standard
          //   built-in Function prototype object as specified in 15.3.3.1.
          // 12. Set the [[Call]] internal property of F as described in
          //   15.3.4.5.1.
          // 13. Set the [[Construct]] internal property of F as described in
          //   15.3.4.5.2.
          // 14. Set the [[HasInstance]] internal property of F as described in
          //   15.3.4.5.3.
          var bound = function () {
  
              if (this instanceof bound) {
                  // 15.3.4.5.2 [[Construct]]
                  // When the [[Construct]] internal method of a function object,
                  // F that was created using the bind function is called with a
                  // list of arguments ExtraArgs, the following steps are taken:
                  // 1. Let target be the value of F's [[TargetFunction]]
                  //   internal property.
                  // 2. If target has no [[Construct]] internal method, a
                  //   TypeError exception is thrown.
                  // 3. Let boundArgs be the value of F's [[BoundArgs]] internal
                  //   property.
                  // 4. Let args be a new list containing the same values as the
                  //   list boundArgs in the same order followed by the same
                  //   values as the list ExtraArgs in the same order.
                  // 5. Return the result of calling the [[Construct]] internal 
                  //   method of target providing args as the arguments.
  
                  var F = function(){};
                  F.prototype = target.prototype;
                  var self = new F;
  
                  var result = target.apply(
                      self,
                      args.concat(slice.call(arguments))
                  );
                  if (result !== null && Object(result) === result)
                      return result;
                  return self;
  
              } else {
                  // 15.3.4.5.1 [[Call]]
                  // When the [[Call]] internal method of a function object, F,
                  // which was created using the bind function is called with a
                  // this value and a list of arguments ExtraArgs, the following
                  // steps are taken:
                  // 1. Let boundArgs be the value of F's [[BoundArgs]] internal
                  //   property.
                  // 2. Let boundThis be the value of F's [[BoundThis]] internal
                  //   property.
                  // 3. Let target be the value of F's [[TargetFunction]] internal
                  //   property.
                  // 4. Let args be a new list containing the same values as the 
                  //   list boundArgs in the same order followed by the same 
                  //   values as the list ExtraArgs in the same order.
                  // 5. Return the result of calling the [[Call]] internal method 
                  //   of target providing boundThis as the this value and 
                  //   providing args as the arguments.
  
                  // equiv: target.call(this, ...boundArgs, ...args)
                  return target.apply(
                      that,
                      args.concat(slice.call(arguments))
                  );
  
              }
  
          };
          // XXX bound.length is never writable, so don't even try
          //
          // 15. If the [[Class]] internal property of Target is "Function", then
          //     a. Let L be the length property of Target minus the length of A.
          //     b. Set the length own property of F to either 0 or L, whichever is 
          //       larger.
          // 16. Else set the length own property of F to 0.
          // 17. Set the attributes of the length own property of F to the values
          //   specified in 15.3.5.1.
  
          // TODO
          // 18. Set the [[Extensible]] internal property of F to true.
          
          // TODO
          // 19. Let thrower be the [[ThrowTypeError]] function Object (13.2.3).
          // 20. Call the [[DefineOwnProperty]] internal method of F with 
          //   arguments "caller", PropertyDescriptor {[[Get]]: thrower, [[Set]]:
          //   thrower, [[Enumerable]]: false, [[Configurable]]: false}, and 
          //   false.
          // 21. Call the [[DefineOwnProperty]] internal method of F with 
          //   arguments "arguments", PropertyDescriptor {[[Get]]: thrower, 
          //   [[Set]]: thrower, [[Enumerable]]: false, [[Configurable]]: false},
          //   and false.
  
          // TODO
          // NOTE Function objects created using Function.prototype.bind do not 
          // have a prototype property or the [[Code]], [[FormalParameters]], and
          // [[Scope]] internal properties.
          // XXX can't delete prototype in pure-js.
  
          // 22. Return F.
          return bound;
      };
  }
  
  // Shortcut to an often accessed properties, in order to avoid multiple
  // dereference that costs universally.
  // _Please note: Shortcuts are defined after `Function.prototype.bind` as we
  // us it in defining shortcuts.
  var call = Function.prototype.call;
  var prototypeOfArray = Array.prototype;
  var prototypeOfObject = Object.prototype;
  var slice = prototypeOfArray.slice;
  var toString = call.bind(prototypeOfObject.toString);
  var owns = call.bind(prototypeOfObject.hasOwnProperty);
  
  // If JS engine supports accessors creating shortcuts.
  var defineGetter;
  var defineSetter;
  var lookupGetter;
  var lookupSetter;
  var supportsAccessors;
  if ((supportsAccessors = owns(prototypeOfObject, "__defineGetter__"))) {
      defineGetter = call.bind(prototypeOfObject.__defineGetter__);
      defineSetter = call.bind(prototypeOfObject.__defineSetter__);
      lookupGetter = call.bind(prototypeOfObject.__lookupGetter__);
      lookupSetter = call.bind(prototypeOfObject.__lookupSetter__);
  }
  
  //
  // Array
  // =====
  //
  
  // ES5 15.4.3.2
  // http://es5.github.com/#x15.4.3.2
  // https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/isArray
  if (!Array.isArray) {
      Array.isArray = function isArray(obj) {
          return toString(obj) == "[object Array]";
      };
  }
  
  // The IsCallable() check in the Array functions
  // has been replaced with a strict check on the
  // internal class of the object to trap cases where
  // the provided function was actually a regular
  // expression literal, which in V8 and
  // JavaScriptCore is a typeof "function".  Only in
  // V8 are regular expression literals permitted as
  // reduce parameters, so it is desirable in the
  // general case for the shim to match the more
  // strict and common behavior of rejecting regular
  // expressions.
  
  // ES5 15.4.4.18
  // http://es5.github.com/#x15.4.4.18
  // https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/array/forEach
  if (!Array.prototype.forEach) {
      Array.prototype.forEach = function forEach(fun /*, thisp*/) {
          var self = toObject(this),
              thisp = arguments[1],
              i = 0,
              length = self.length >>> 0;
  
          // If no callback function or if callback is not a callable function
          if (toString(fun) != "[object Function]") {
              throw new TypeError(); // TODO message
          }
  
          while (i < length) {
              if (i in self) {
                  // Invoke the callback function with call, passing arguments:
                  // context, property value, property key, thisArg object context
                  fun.call(thisp, self[i], i, self);
              }
              i++;
          }
      };
  }
  
  // ES5 15.4.4.19
  // http://es5.github.com/#x15.4.4.19
  // https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Objects/Array/map
  if (!Array.prototype.map) {
      Array.prototype.map = function map(fun /*, thisp*/) {
          var self = toObject(this),
              length = self.length >>> 0,
              result = Array(length),
              thisp = arguments[1];
  
          // If no callback function or if callback is not a callable function
          if (toString(fun) != "[object Function]") {
              throw new TypeError(); // TODO message
          }
  
          for (var i = 0; i < length; i++) {
              if (i in self)
                  result[i] = fun.call(thisp, self[i], i, self);
          }
          return result;
      };
  }
  
  // ES5 15.4.4.20
  // http://es5.github.com/#x15.4.4.20
  // https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Objects/Array/filter
  if (!Array.prototype.filter) {
      Array.prototype.filter = function filter(fun /*, thisp */) {
          var self = toObject(this),
              length = self.length >>> 0,
              result = [],
              thisp = arguments[1];
  
          // If no callback function or if callback is not a callable function
          if (toString(fun) != "[object Function]") {
              throw new TypeError(); // TODO message
          }
  
          for (var i = 0; i < length; i++) {
              if (i in self && fun.call(thisp, self[i], i, self))
                  result.push(self[i]);
          }
          return result;
      };
  }
  
  // ES5 15.4.4.16
  // http://es5.github.com/#x15.4.4.16
  // https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/every
  if (!Array.prototype.every) {
      Array.prototype.every = function every(fun /*, thisp */) {
          var self = toObject(this),
              length = self.length >>> 0,
              thisp = arguments[1];
  
          // If no callback function or if callback is not a callable function
          if (toString(fun) != "[object Function]") {
              throw new TypeError(); // TODO message
          }
  
          for (var i = 0; i < length; i++) {
              if (i in self && !fun.call(thisp, self[i], i, self))
                  return false;
          }
          return true;
      };
  }
  
  // ES5 15.4.4.17
  // http://es5.github.com/#x15.4.4.17
  // https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/some
  if (!Array.prototype.some) {
      Array.prototype.some = function some(fun /*, thisp */) {
          var self = toObject(this),
              length = self.length >>> 0,
              thisp = arguments[1];
  
          // If no callback function or if callback is not a callable function
          if (toString(fun) != "[object Function]") {
              throw new TypeError(); // TODO message
          }
  
          for (var i = 0; i < length; i++) {
              if (i in self && fun.call(thisp, self[i], i, self))
                  return true;
          }
          return false;
      };
  }
  
  // ES5 15.4.4.21
  // http://es5.github.com/#x15.4.4.21
  // https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Objects/Array/reduce
  if (!Array.prototype.reduce) {
      Array.prototype.reduce = function reduce(fun /*, initial*/) {
          var self = toObject(this),
              length = self.length >>> 0;
  
          // If no callback function or if callback is not a callable function
          if (toString(fun) != "[object Function]") {
              throw new TypeError(); // TODO message
          }
  
          // no value to return if no initial value and an empty array
          if (!length && arguments.length == 1)
              throw new TypeError(); // TODO message
  
          var i = 0;
          var result;
          if (arguments.length >= 2) {
              result = arguments[1];
          } else {
              do {
                  if (i in self) {
                      result = self[i++];
                      break;
                  }
  
                  // if array contains no values, no initial value to return
                  if (++i >= length)
                      throw new TypeError(); // TODO message
              } while (true);
          }
  
          for (; i < length; i++) {
              if (i in self)
                  result = fun.call(void 0, result, self[i], i, self);
          }
  
          return result;
      };
  }
  
  // ES5 15.4.4.22
  // http://es5.github.com/#x15.4.4.22
  // https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Objects/Array/reduceRight
  if (!Array.prototype.reduceRight) {
      Array.prototype.reduceRight = function reduceRight(fun /*, initial*/) {
          var self = toObject(this),
              length = self.length >>> 0;
  
          // If no callback function or if callback is not a callable function
          if (toString(fun) != "[object Function]") {
              throw new TypeError(); // TODO message
          }
  
          // no value to return if no initial value, empty array
          if (!length && arguments.length == 1)
              throw new TypeError(); // TODO message
  
          var result, i = length - 1;
          if (arguments.length >= 2) {
              result = arguments[1];
          } else {
              do {
                  if (i in self) {
                      result = self[i--];
                      break;
                  }
  
                  // if array contains no values, no initial value to return
                  if (--i < 0)
                      throw new TypeError(); // TODO message
              } while (true);
          }
  
          do {
              if (i in this)
                  result = fun.call(void 0, result, self[i], i, self);
          } while (i--);
  
          return result;
      };
  }
  
  // ES5 15.4.4.14
  // http://es5.github.com/#x15.4.4.14
  // https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/indexOf
  if (!Array.prototype.indexOf) {
      Array.prototype.indexOf = function indexOf(sought /*, fromIndex */ ) {
          var self = toObject(this),
              length = self.length >>> 0;
  
          if (!length)
              return -1;
  
          var i = 0;
          if (arguments.length > 1)
              i = toInteger(arguments[1]);
  
          // handle negative indices
          i = i >= 0 ? i : Math.max(0, length + i);
          for (; i < length; i++) {
              if (i in self && self[i] === sought) {
                  return i;
              }
          }
          return -1;
      };
  }
  
  // ES5 15.4.4.15
  // http://es5.github.com/#x15.4.4.15
  // https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/lastIndexOf
  if (!Array.prototype.lastIndexOf) {
      Array.prototype.lastIndexOf = function lastIndexOf(sought /*, fromIndex */) {
          var self = toObject(this),
              length = self.length >>> 0;
  
          if (!length)
              return -1;
          var i = length - 1;
          if (arguments.length > 1)
              i = Math.min(i, toInteger(arguments[1]));
          // handle negative indices
          i = i >= 0 ? i : length - Math.abs(i);
          for (; i >= 0; i--) {
              if (i in self && sought === self[i])
                  return i;
          }
          return -1;
      };
  }
  
  //
  // Object
  // ======
  //
  
  // ES5 15.2.3.2
  // http://es5.github.com/#x15.2.3.2
  if (!Object.getPrototypeOf) {
      // https://github.com/kriskowal/es5-shim/issues#issue/2
      // http://ejohn.org/blog/objectgetprototypeof/
      // recommended by fschaefer on github
      Object.getPrototypeOf = function getPrototypeOf(object) {
          return object.__proto__ || (
              object.constructor ?
              object.constructor.prototype :
              prototypeOfObject
          );
      };
  }
  
  // ES5 15.2.3.3
  // http://es5.github.com/#x15.2.3.3
  if (!Object.getOwnPropertyDescriptor) {
      var ERR_NON_OBJECT = "Object.getOwnPropertyDescriptor called on a " +
                           "non-object: ";
      Object.getOwnPropertyDescriptor = function getOwnPropertyDescriptor(object, property) {
          if ((typeof object != "object" && typeof object != "function") || object === null)
              throw new TypeError(ERR_NON_OBJECT + object);
          // If object does not owns property return undefined immediately.
          if (!owns(object, property))
              return;
  
          var descriptor, getter, setter;
  
          // If object has a property then it's for sure both `enumerable` and
          // `configurable`.
          descriptor =  { enumerable: true, configurable: true };
  
          // If JS engine supports accessor properties then property may be a
          // getter or setter.
          if (supportsAccessors) {
              // Unfortunately `__lookupGetter__` will return a getter even
              // if object has own non getter property along with a same named
              // inherited getter. To avoid misbehavior we temporary remove
              // `__proto__` so that `__lookupGetter__` will return getter only
              // if it's owned by an object.
              var prototype = object.__proto__;
              object.__proto__ = prototypeOfObject;
  
              var getter = lookupGetter(object, property);
              var setter = lookupSetter(object, property);
  
              // Once we have getter and setter we can put values back.
              object.__proto__ = prototype;
  
              if (getter || setter) {
                  if (getter) descriptor.get = getter;
                  if (setter) descriptor.set = setter;
  
                  // If it was accessor property we're done and return here
                  // in order to avoid adding `value` to the descriptor.
                  return descriptor;
              }
          }
  
          // If we got this far we know that object has an own property that is
          // not an accessor so we set it as a value and return descriptor.
          descriptor.value = object[property];
          return descriptor;
      };
  }
  
  // ES5 15.2.3.4
  // http://es5.github.com/#x15.2.3.4
  if (!Object.getOwnPropertyNames) {
      Object.getOwnPropertyNames = function getOwnPropertyNames(object) {
          return Object.keys(object);
      };
  }
  
  // ES5 15.2.3.5
  // http://es5.github.com/#x15.2.3.5
  if (!Object.create) {
      var createEmpty;
      if (Object.prototype.__proto__ === null) {
          createEmpty = function () {
              return { "__proto__": null };
          };
      } else {
          // In old IE __proto__ can't be used to manually set `null`
          createEmpty = function () {
              var empty = {};
              for (var i in empty)
                  empty[i] = null;
              empty.constructor =
              empty.hasOwnProperty =
              empty.propertyIsEnumerable =
              empty.isPrototypeOf =
              empty.toLocaleString =
              empty.toString =
              empty.valueOf =
              empty.__proto__ = null;
              return empty;
          }
      }
  
      Object.create = function create(prototype, properties) {
          var object;
          if (prototype === null) {
              object = createEmpty();
          } else {
              if (typeof prototype != "object")
                  throw new TypeError("typeof prototype["+(typeof prototype)+"] != 'object'");
              var Type = function () {};
              Type.prototype = prototype;
              object = new Type();
              // IE has no built-in implementation of `Object.getPrototypeOf`
              // neither `__proto__`, but this manually setting `__proto__` will
              // guarantee that `Object.getPrototypeOf` will work as expected with
              // objects created using `Object.create`
              object.__proto__ = prototype;
          }
          if (properties !== void 0)
              Object.defineProperties(object, properties);
          return object;
      };
  }
  
  // ES5 15.2.3.6
  // http://es5.github.com/#x15.2.3.6
  
  // Patch for WebKit and IE8 standard mode
  // Designed by hax <hax.github.com>
  // related issue: https://github.com/kriskowal/es5-shim/issues#issue/5
  // IE8 Reference:
  //     http://msdn.microsoft.com/en-us/library/dd282900.aspx
  //     http://msdn.microsoft.com/en-us/library/dd229916.aspx
  // WebKit Bugs:
  //     https://bugs.webkit.org/show_bug.cgi?id=36423
  
  function doesDefinePropertyWork(object) {
      try {
          Object.defineProperty(object, "sentinel", {});
          return "sentinel" in object;
      } catch (exception) {
          // returns falsy
      }
  }
  
  // check whether defineProperty works if it's given. Otherwise,
  // shim partially.
  if (Object.defineProperty) {
      var definePropertyWorksOnObject = doesDefinePropertyWork({});
      var definePropertyWorksOnDom = typeof document == "undefined" ||
          doesDefinePropertyWork(document.createElement("div"));
      if (!definePropertyWorksOnObject || !definePropertyWorksOnDom) {
          var definePropertyFallback = Object.defineProperty;
      }
  }
  
  if (!Object.defineProperty || definePropertyFallback) {
      var ERR_NON_OBJECT_DESCRIPTOR = "Property description must be an object: ";
      var ERR_NON_OBJECT_TARGET = "Object.defineProperty called on non-object: "
      var ERR_ACCESSORS_NOT_SUPPORTED = "getters & setters can not be defined " +
                                        "on this javascript engine";
  
      Object.defineProperty = function defineProperty(object, property, descriptor) {
          if ((typeof object != "object" && typeof object != "function") || object === null)
              throw new TypeError(ERR_NON_OBJECT_TARGET + object);
          if ((typeof descriptor != "object" && typeof descriptor != "function") || descriptor === null)
              throw new TypeError(ERR_NON_OBJECT_DESCRIPTOR + descriptor);
  
          // make a valiant attempt to use the real defineProperty
          // for I8's DOM elements.
          if (definePropertyFallback) {
              try {
                  return definePropertyFallback.call(Object, object, property, descriptor);
              } catch (exception) {
                  // try the shim if the real one doesn't work
              }
          }
  
          // If it's a data property.
          if (owns(descriptor, "value")) {
              // fail silently if "writable", "enumerable", or "configurable"
              // are requested but not supported
              /*
              // alternate approach:
              if ( // can't implement these features; allow false but not true
                  !(owns(descriptor, "writable") ? descriptor.writable : true) ||
                  !(owns(descriptor, "enumerable") ? descriptor.enumerable : true) ||
                  !(owns(descriptor, "configurable") ? descriptor.configurable : true)
              )
                  throw new RangeError(
                      "This implementation of Object.defineProperty does not " +
                      "support configurable, enumerable, or writable."
                  );
              */
  
              if (supportsAccessors && (lookupGetter(object, property) ||
                                        lookupSetter(object, property)))
              {
                  // As accessors are supported only on engines implementing
                  // `__proto__` we can safely override `__proto__` while defining
                  // a property to make sure that we don't hit an inherited
                  // accessor.
                  var prototype = object.__proto__;
                  object.__proto__ = prototypeOfObject;
                  // Deleting a property anyway since getter / setter may be
                  // defined on object itself.
                  delete object[property];
                  object[property] = descriptor.value;
                  // Setting original `__proto__` back now.
                  object.__proto__ = prototype;
              } else {
                  object[property] = descriptor.value;
              }
          } else {
              if (!supportsAccessors)
                  throw new TypeError(ERR_ACCESSORS_NOT_SUPPORTED);
              // If we got that far then getters and setters can be defined !!
              if (owns(descriptor, "get"))
                  defineGetter(object, property, descriptor.get);
              if (owns(descriptor, "set"))
                  defineSetter(object, property, descriptor.set);
          }
  
          return object;
      };
  }
  
  // ES5 15.2.3.7
  // http://es5.github.com/#x15.2.3.7
  if (!Object.defineProperties) {
      Object.defineProperties = function defineProperties(object, properties) {
          for (var property in properties) {
              if (owns(properties, property))
                  Object.defineProperty(object, property, properties[property]);
          }
          return object;
      };
  }
  
  // ES5 15.2.3.8
  // http://es5.github.com/#x15.2.3.8
  if (!Object.seal) {
      Object.seal = function seal(object) {
          // this is misleading and breaks feature-detection, but
          // allows "securable" code to "gracefully" degrade to working
          // but insecure code.
          return object;
      };
  }
  
  // ES5 15.2.3.9
  // http://es5.github.com/#x15.2.3.9
  if (!Object.freeze) {
      Object.freeze = function freeze(object) {
          // this is misleading and breaks feature-detection, but
          // allows "securable" code to "gracefully" degrade to working
          // but insecure code.
          return object;
      };
  }
  
  // detect a Rhino bug and patch it
  try {
      Object.freeze(function () {});
  } catch (exception) {
      Object.freeze = (function freeze(freezeObject) {
          return function freeze(object) {
              if (typeof object == "function") {
                  return object;
              } else {
                  return freezeObject(object);
              }
          };
      })(Object.freeze);
  }
  
  // ES5 15.2.3.10
  // http://es5.github.com/#x15.2.3.10
  if (!Object.preventExtensions) {
      Object.preventExtensions = function preventExtensions(object) {
          // this is misleading and breaks feature-detection, but
          // allows "securable" code to "gracefully" degrade to working
          // but insecure code.
          return object;
      };
  }
  
  // ES5 15.2.3.11
  // http://es5.github.com/#x15.2.3.11
  if (!Object.isSealed) {
      Object.isSealed = function isSealed(object) {
          return false;
      };
  }
  
  // ES5 15.2.3.12
  // http://es5.github.com/#x15.2.3.12
  if (!Object.isFrozen) {
      Object.isFrozen = function isFrozen(object) {
          return false;
      };
  }
  
  // ES5 15.2.3.13
  // http://es5.github.com/#x15.2.3.13
  if (!Object.isExtensible) {
      Object.isExtensible = function isExtensible(object) {
          // 1. If Type(O) is not Object throw a TypeError exception.
          if (Object(object) === object) {
              throw new TypeError(); // TODO message
          }
          // 2. Return the Boolean value of the [[Extensible]] internal property of O.
          var name = '';
          while (owns(object, name)) {
              name += '?';
          }
          object[name] = true;
          var returnValue = owns(object, name);
          delete object[name];
          return returnValue;
      };
  }
  
  // ES5 15.2.3.14
  // http://es5.github.com/#x15.2.3.14
  if (!Object.keys) {
      // http://whattheheadsaid.com/2010/10/a-safer-object-keys-compatibility-implementation
      var hasDontEnumBug = true,
          dontEnums = [
              "toString",
              "toLocaleString",
              "valueOf",
              "hasOwnProperty",
              "isPrototypeOf",
              "propertyIsEnumerable",
              "constructor"
          ],
          dontEnumsLength = dontEnums.length;
  
      for (var key in {"toString": null})
          hasDontEnumBug = false;
  
      Object.keys = function keys(object) {
  
          if ((typeof object != "object" && typeof object != "function") || object === null)
              throw new TypeError("Object.keys called on a non-object");
  
          var keys = [];
          for (var name in object) {
              if (owns(object, name)) {
                  keys.push(name);
              }
          }
  
          if (hasDontEnumBug) {
              for (var i = 0, ii = dontEnumsLength; i < ii; i++) {
                  var dontEnum = dontEnums[i];
                  if (owns(object, dontEnum)) {
                      keys.push(dontEnum);
                  }
              }
          }
  
          return keys;
      };
  
  }
  
  //
  // Date
  // ====
  //
  
  // ES5 15.9.5.43
  // http://es5.github.com/#x15.9.5.43
  // This function returns a String value represent the instance in time 
  // represented by this Date object. The format of the String is the Date Time 
  // string format defined in 15.9.1.15. All fields are present in the String. 
  // The time zone is always UTC, denoted by the suffix Z. If the time value of 
  // this object is not a finite Number a RangeError exception is thrown.
  if (!Date.prototype.toISOString || (new Date(-62198755200000).toISOString().indexOf('-000001') === -1)) {
      Date.prototype.toISOString = function toISOString() {
          var result, length, value, year;
          if (!isFinite(this))
              throw new RangeError;
  
          // the date time string format is specified in 15.9.1.15.
          result = [this.getUTCMonth() + 1, this.getUTCDate(),
              this.getUTCHours(), this.getUTCMinutes(), this.getUTCSeconds()];
          year = this.getUTCFullYear();
          year = (year < 0 ? '-' : (year > 9999 ? '+' : '')) + ('00000' + Math.abs(year)).slice(0 <= year && year <= 9999 ? -4 : -6);
  
          length = result.length;
          while (length--) {
              value = result[length];
              // pad months, days, hours, minutes, and seconds to have two digits.
              if (value < 10)
                  result[length] = "0" + value;
          }
          // pad milliseconds to have three digits.
          return year + "-" + result.slice(0, 2).join("-") + "T" + result.slice(2).join(":") + "." +
              ("000" + this.getUTCMilliseconds()).slice(-3) + "Z";
      }
  }
  
  // ES5 15.9.4.4
  // http://es5.github.com/#x15.9.4.4
  if (!Date.now) {
      Date.now = function now() {
          return new Date().getTime();
      };
  }
  
  // ES5 15.9.5.44
  // http://es5.github.com/#x15.9.5.44
  // This function provides a String representation of a Date object for use by 
  // JSON.stringify (15.12.3).
  if (!Date.prototype.toJSON) {
      Date.prototype.toJSON = function toJSON(key) {
          // When the toJSON method is called with argument key, the following 
          // steps are taken:
  
          // 1.  Let O be the result of calling ToObject, giving it the this
          // value as its argument.
          // 2. Let tv be ToPrimitive(O, hint Number).
          // 3. If tv is a Number and is not finite, return null.
          // XXX
          // 4. Let toISO be the result of calling the [[Get]] internal method of
          // O with argument "toISOString".
          // 5. If IsCallable(toISO) is false, throw a TypeError exception.
          if (typeof this.toISOString != "function")
              throw new TypeError(); // TODO message
          // 6. Return the result of calling the [[Call]] internal method of
          //  toISO with O as the this value and an empty argument list.
          return this.toISOString();
  
          // NOTE 1 The argument is ignored.
  
          // NOTE 2 The toJSON function is intentionally generic; it does not
          // require that its this value be a Date object. Therefore, it can be
          // transferred to other kinds of objects for use as a method. However,
          // it does require that any such object have a toISOString method. An
          // object is free to use the argument key to filter its
          // stringification.
      };
  }
  
  // ES5 15.9.4.2
  // http://es5.github.com/#x15.9.4.2
  // based on work shared by Daniel Friesen (dantman)
  // http://gist.github.com/303249
  if (Date.parse("+275760-09-13T00:00:00.000Z") !== 8.64e15) {
      // XXX global assignment won't work in embeddings that use
      // an alternate object for the context.
      Date = (function(NativeDate) {
  
          // Date.length === 7
          var Date = function Date(Y, M, D, h, m, s, ms) {
              var length = arguments.length;
              if (this instanceof NativeDate) {
                  var date = length == 1 && String(Y) === Y ? // isString(Y)
                      // We explicitly pass it through parse:
                      new NativeDate(Date.parse(Y)) :
                      // We have to manually make calls depending on argument
                      // length here
                      length >= 7 ? new NativeDate(Y, M, D, h, m, s, ms) :
                      length >= 6 ? new NativeDate(Y, M, D, h, m, s) :
                      length >= 5 ? new NativeDate(Y, M, D, h, m) :
                      length >= 4 ? new NativeDate(Y, M, D, h) :
                      length >= 3 ? new NativeDate(Y, M, D) :
                      length >= 2 ? new NativeDate(Y, M) :
                      length >= 1 ? new NativeDate(Y) :
                                    new NativeDate();
                  // Prevent mixups with unfixed Date object
                  date.constructor = Date;
                  return date;
              }
              return NativeDate.apply(this, arguments);
          };
  
          // 15.9.1.15 Date Time String Format.
          var isoDateExpression = new RegExp("^" +
              "(\\d{4}|[\+\-]\\d{6})" + // four-digit year capture or sign + 6-digit extended year
              "(?:-(\\d{2})" + // optional month capture
              "(?:-(\\d{2})" + // optional day capture
              "(?:" + // capture hours:minutes:seconds.milliseconds
                  "T(\\d{2})" + // hours capture
                  ":(\\d{2})" + // minutes capture
                  "(?:" + // optional :seconds.milliseconds
                      ":(\\d{2})" + // seconds capture
                      "(?:\\.(\\d{3}))?" + // milliseconds capture
                  ")?" +
              "(?:" + // capture UTC offset component
                  "Z|" + // UTC capture
                  "(?:" + // offset specifier +/-hours:minutes
                      "([-+])" + // sign capture
                      "(\\d{2})" + // hours offset capture
                      ":(\\d{2})" + // minutes offset capture
                  ")" +
              ")?)?)?)?" +
          "$");
  
          // Copy any custom methods a 3rd party library may have added
          for (var key in NativeDate)
              Date[key] = NativeDate[key];
  
          // Copy "native" methods explicitly; they may be non-enumerable
          Date.now = NativeDate.now;
          Date.UTC = NativeDate.UTC;
          Date.prototype = NativeDate.prototype;
          Date.prototype.constructor = Date;
  
          // Upgrade Date.parse to handle simplified ISO 8601 strings
          Date.parse = function parse(string) {
              var match = isoDateExpression.exec(string);
              if (match) {
                  match.shift(); // kill match[0], the full match
                  // parse months, days, hours, minutes, seconds, and milliseconds
                  for (var i = 1; i < 7; i++) {
                      // provide default values if necessary
                      match[i] = +(match[i] || (i < 3 ? 1 : 0));
                      // match[1] is the month. Months are 0-11 in JavaScript
                      // `Date` objects, but 1-12 in ISO notation, so we
                      // decrement.
                      if (i == 1)
                          match[i]--;
                  }
  
                  // parse the UTC offset component
                  var minuteOffset = +match.pop(), hourOffset = +match.pop(), sign = match.pop();
  
                  // compute the explicit time zone offset if specified
                  var offset = 0;
                  if (sign) {
                      // detect invalid offsets and return early
                      if (hourOffset > 23 || minuteOffset > 59)
                          return NaN;
  
                      // express the provided time zone offset in minutes. The offset is
                      // negative for time zones west of UTC; positive otherwise.
                      offset = (hourOffset * 60 + minuteOffset) * 6e4 * (sign == "+" ? -1 : 1);
                  }
  
                  // Date.UTC for years between 0 and 99 converts year to 1900 + year
                  // The Gregorian calendar has a 400-year cycle, so 
                  // to Date.UTC(year + 400, .... ) - 12622780800000 == Date.UTC(year, ...),
                  // where 12622780800000 - number of milliseconds in Gregorian calendar 400 years
                  var year = +match[0];
                  if (0 <= year && year <= 99) {
                      match[0] = year + 400;
                      return NativeDate.UTC.apply(this, match) + offset - 12622780800000;
                  }
  
                  // compute a new UTC date value, accounting for the optional offset
                  return NativeDate.UTC.apply(this, match) + offset;
              }
              return NativeDate.parse.apply(this, arguments);
          };
  
          return Date;
      })(Date);
  }
  
  //
  // String
  // ======
  //
  
  // ES5 15.5.4.20
  // http://es5.github.com/#x15.5.4.20
  var ws = "\x09\x0A\x0B\x0C\x0D\x20\xA0\u1680\u180E\u2000\u2001\u2002\u2003" +
      "\u2004\u2005\u2006\u2007\u2008\u2009\u200A\u202F\u205F\u3000\u2028" +
      "\u2029\uFEFF";
  if (!String.prototype.trim || ws.trim()) {
      // http://blog.stevenlevithan.com/archives/faster-trim-javascript
      // http://perfectionkills.com/whitespace-deviations/
      ws = "[" + ws + "]";
      var trimBeginRegexp = new RegExp("^" + ws + ws + "*"),
          trimEndRegexp = new RegExp(ws + ws + "*$");
      String.prototype.trim = function trim() {
          return String(this).replace(trimBeginRegexp, "").replace(trimEndRegexp, "");
      };
  }
  
  //
  // Util
  // ======
  //
  
  // ES5 9.4
  // http://es5.github.com/#x9.4
  // http://jsperf.com/to-integer
  var toInteger = function (n) {
      n = +n;
      if (n !== n) // isNaN
          n = 0;
      else if (n !== 0 && n !== (1/0) && n !== -(1/0))
          n = (n > 0 || -1) * Math.floor(Math.abs(n));
      return n;
  };
  
  var prepareString = "a"[0] != "a",
      // ES5 9.9
      // http://es5.github.com/#x9.9
      toObject = function (o) {
          if (o == null) { // this matches both null and undefined
              throw new TypeError(); // TODO message
          }
          // If the implementation doesn't support by-index access of
          // string characters (ex. IE < 7), split the string
          if (prepareString && typeof o == "string" && o) {
              return o.split("");
          }
          return Object(o);
      };
  });
  