title: Mutation Observer is undefined
body: <p>I am attempting to fix and issue with my code. I was originally using DOMNodeRemoved and DOMNodeInserted for keeping an eye on an element within a page I am working on. They worked well but did not function in IE. So I started trying to work with a MutationObserver.</p>
  
  <p>Here is my Code it's called on onPageInit(the callback writes to the console but I disabled it since IE no longer supports console):</p>
  
  <pre><code>var callback = function(allmutations){
      allmutations.map( function(mr){
          var mt = 'Mutation type: ' + mr.type;  // log the type of mutation
          mt += 'Mutation target: ' + mr.target; // log the node affected.
          //console.log( mt );
      })
  }
  mo = new MutationObserver(callback),
  options = {
      // required, and observes additions or deletion of child nodes.
      'childList': true, 
      // observes the addition or deletion of "grandchild" nodes.
      'subtree': true
  }
  alert('its alive');
  mo.observe(document.body, options);
  </code></pre>
  
  <p>It works fine in chrome, however for some reason falls flat in IE. I get a message box during load of the page that says :</p>
  
  <pre><code>An unexpected error occurred in a script running on this page.
  onPageInit(pageInit)
  scriptname
  
  JS_EXCEPTION
  TypeError 'MutationObserver' is undefined
  </code></pre>
  
  <p>Am I doing something wrong? 
  Additional info:
  Page is a netsuite page, running jQuery 1.7.2 (if it matters)</p>