Implementing CustomElement's attributeChanged callback.

pkg/custom_element/lib/custom-elements.debug.js

 // Copyright (c) 2012 The Polymer Authors. All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //    * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //    * Redistributions in binary form must reproduce the above
 // copyright notice, this list of conditions and the following disclaimer
@@ skipping 1189 matching lines @@
 
   function overrideAttributeApi(prototype) {
     // overrides to implement callbacks
     // TODO(sjmiles): should support access via .attributes NamedNodeMap
     // TODO(sjmiles): preserves user defined overrides, if any
     var setAttribute = prototype.setAttribute;
     prototype.setAttribute = function(name, value) {
       changeAttribute.call(this, name, value, setAttribute);
     }
     var removeAttribute = prototype.removeAttribute;
-    prototype.removeAttribute = function(name, value) {
-      changeAttribute.call(this, name, value, removeAttribute);
+    prototype.removeAttribute = function(name) {
+      changeAttribute.call(this, name, null, removeAttribute);
     }
   }
 
   function changeAttribute(name, value, operation) {
     var oldValue = this.getAttribute(name);
     operation.apply(this, arguments);
     if (this.attributeChangedCallback
         && (this.getAttribute(name) !== oldValue)) {
-      this.attributeChangedCallback(name, oldValue);
+      this.attributeChangedCallback(name, oldValue, value);
     }
   }
 
   // element registry (maps tag names to definitions)
 
   var registry = {};
 
   function registerDefinition(name, definition) {
     if (registry[name]) {
       throw new Error('Cannot register a tag more than once');
@@ skipping 199 matching lines @@
 // include .host reference
 if (HTMLElement.prototype.createShadowRoot) {
   var originalCreateShadowRoot = HTMLElement.prototype.createShadowRoot;
   HTMLElement.prototype.createShadowRoot = function() {
     var root = originalCreateShadowRoot.call(this);
     root.host = this;
     return root;
   }
 }
 })();