[pkg:mutation_observer] fix 12132, ie9 support

pkg/mutation_observer/lib/mutation_observer.js

 /*
  * Copyright 2013 The Polymer Authors. All rights reserved.
  * Use of this source code is goverened by a BSD-style
  * license that can be found in the LICENSE file.
  */
 
 // TODO(jmesserly): polyfill does not have feature testing or the definition of
 // SideTable. The extra code is from:
 // https://github.com/Polymer/CustomElements/blob/master/src/MutationObserver.js
 // https://github.com/Polymer/CustomElements/blob/master/src/sidetable.js
 // I also renamed JsMutationObserver -> MutationObserver to correctly interact
 // with dart2js interceptors.
+
 if (!window.MutationObserver && !window.WebKitMutationObserver) {
 
 (function(global) {
   // SideTable is a weak map where possible. If WeakMap is not available the
   // association is stored as an expando property.
   var SideTable;
   // TODO(arv): WeakMap does not allow for Node etc to be keys in Firefox
   if (typeof WeakMap !== 'undefined' && navigator.userAgent.indexOf('Firefox/') < 0) {
     SideTable = WeakMap;
   } else {
@@ skipping 153 matching lines @@
    * @constructor
    */
   function MutationObserver(callback) {
     this.callback_ = callback;
     this.nodes_ = [];
     this.records_ = [];
     this.uid_ = ++uidCounter;
   }
 
   MutationObserver.prototype = {
-    // TODO(jmesserly): why is this necessary?
-    get constructor() { return MutationObserver; },
-
     observe: function(target, options) {
       target = wrapIfNeeded(target);
 
       // 1.1
       if (!options.childList && !options.attributes && !options.characterData ||
 
           // 1.2
           options.attributeOldValue && !options.attributes ||
 
           // 1.3
@@ skipping 72 matching lines @@
     this.target = target;
     this.addedNodes = [];
     this.removedNodes = [];
     this.previousSibling = null;
     this.nextSibling = null;
     this.attributeName = null;
     this.attributeNamespace = null;
     this.oldValue = null;
   }
 
+  // TODO(jmesserly): this fixes the interceptor dispatch on IE.
+  // Not sure why this is necessary.
+  MutationObserver.prototype.constructor = MutationObserver;
+  MutationObserver.name = 'MutationObserver';
+  MutationRecord.prototype.constructor = MutationRecord;
+  MutationRecord.name = 'MutationRecord';
+
   function copyMutationRecord(original) {
     var record = new MutationRecord(original.type, original.target);
     record.addedNodes = original.addedNodes.slice();
     record.removedNodes = original.removedNodes.slice();
     record.previousSibling = original.previousSibling;
     record.nextSibling = original.nextSibling;
     record.attributeName = original.attributeName;
     record.attributeNamespace = original.attributeNamespace;
     record.oldValue = original.oldValue;
     return record;
@@ skipping 283 matching lines @@
       }
 
       clearRecords();
     }
   };
 
   global.MutationObserver = MutationObserver;
 })(window);
 
 }