Optimize dartium dart:html bindings so real world application performance is acceptable. Improves d…

tools/dom/src/dartium_CustomElementSupport.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart.dom.html;
 
 /// Dartium ElementUpgrader implementation.
 class _VMElementUpgrader implements ElementUpgrader {
   final Type _type;
   final Type _nativeType;
@@ skipping 11 matching lines @@
       }
     } else {
       if (document.createElement(extendsTag).runtimeType != _nativeType) {
         throw new UnsupportedError(
             'extendsTag does not match base native class');
       }
     }
   }
 
   Element upgrade(element) {
-    var jsObject;
     var tag;
     var isNativeElementExtension = false;
 
     try {
       tag = _getCustomElementName(element);
     } catch (e) {
       isNativeElementExtension = element.localName == _extendsTag;
     }
 
     if (element.runtimeType == HtmlElement || element.runtimeType == TemplateElement) {
       if (tag != _extendsTag) {
         throw new UnsupportedError('$tag is not registered.');
       }
-      jsObject = unwrap_jso(element);
     } else if (element.runtimeType == js.JsObject) {
       // It's a Polymer core element (written in JS).
-      jsObject = element;
     } else if (isNativeElementExtension) {
       // Extending a native element.
-      jsObject = element.blink_jsObject;
+      // TODO(jacobr): make sure we haven't busted this case.
 
       // Element to extend is the real tag.
       tag = element.localName;
     } else if (tag != null && element.localName != tag) {
       throw new UnsupportedError('Element is incorrect type. Got ${element.runtimeType}, expected native Html or Svg element to extend.');
     } else if (tag == null) {
       throw new UnsupportedError('Element is incorrect type. Got ${element.runtimeType}, expected HtmlElement/JsObject.');
     }
 
-    // Remember Dart class to tagName for any upgrading done in wrap_jso.
+    // Remember Dart class to tagName for any upgrading
     addCustomElementType(tag, _type, _extendsTag);
 
-    return _createCustomUpgrader(_type, jsObject);
+    // TODO(jacobr): XXX validate that this method still works.
+    return _createCustomUpgrader(_type, element);
   }
 }
 
 /// Validates that the custom type is properly formed-
 ///
 /// * Is a user-defined class.
 /// * Has a created constructor with zero args.
 /// * Derives from an Element subclass.
 ///
 /// Then returns the native base class.
@@ skipping 40 matching lines @@
   return nativeClass;
 }
 
 
 bool _isBuiltinType(ClassMirror cls) {
   // TODO(vsm): Find a less hackish way to do this.
   LibraryMirror lib = cls.owner;
   String libName = lib.uri.toString();
   return libName.startsWith('dart:');
 }