anchor.diff:    // This string should be referenced wherever JavaScript code makes assumptions
     // on the mixin format.
     static final String mixinFormatDescription =
  -      "Mixins have no constructor, but a reference to their mixin class.";
  +      "Mixins have a reference to their mixin class at the place of the usual"
  +      "constructor. If they are instantiated the constructor follows the"
  +      "reference.";
   
     js.Expression emitClass(Class cls) {
       List elements = [js.string(cls.superclassName),
  
positive.code:       MixinApplication mixin = cls;
        elements.add(js.string(mixin.mixinClass.name));
        elements.add(js.number(mixin.mixinClass.holder.index));
      } else {
        elements.add(_generateConstructor(cls));
      }
  
negative.code:     descriptor = compile(name, descriptor);
      var prototype = determinePrototype(descriptor);
      var constructor;
      var functionsIndex;
      // $mixinFormatDescription.
      if (typeof descriptor[2] !== 'function') {
        fillPrototypeWithMixedIn(descriptor[2], descriptor[3], prototype);
        // descriptor[4] contains the constructor if the mixin application is
        // directly instantiated.
        if (typeof descriptor[4] === 'function') {
          constructor = descriptor[4];
          functionsIndex = 5;
        } else {
          constructor = function() {};
          functionsIndex = 4;
        }
      } else {
        constructor = descriptor[2];
        functionsIndex = 3;
      }
  
      for (var i = functionsIndex; i < descriptor.length; i += 2) {
        parseFunctionDescriptor(prototype, descriptor[i], descriptor[i + 1]);
      }
  
      constructor.builtin\$cls = name;  // Needed for RTI.
      constructor.prototype = prototype;
      prototype[#operatorIsPrefix + name] = constructor;
  