[web_components] update web_components and polymer.js

pkg/polymer/lib/src/js/use_native_dartium_shadowdom.js

 // Prevent polyfilled JS Shadow DOM in Dartium
 // We need this if we want Dart code to be able to interoperate with Polymer.js
 // code that also uses Shadow DOM.
 // TODO(jmesserly): we can remove this code once platform.js is correctly
 // feature detecting Shadow DOM in Dartium.
 if (navigator.userAgent.indexOf('(Dart)') !== -1) {
   window.Platform = window.Platform || {};
   Platform.flags = Platform.flags || {};
   Platform.flags.shadow = 'native';
+
+  // Note: Dartium 34 hasn't turned on the unprefixed Shadow DOM
+  // (this happens in Chrome 35), so unless "enable experimental platform
+  // features" is enabled, things will break. So we expose them as unprefixed
+  // names instead.
+  var proto = Element.prototype;

[Jennifer Messerly, 2014/04/02 23:43:50]

this is the new change. it makes polymer.js code in Dartium work properly, even
if "enable experimental platform features" isn't turned on in about:flags

+  if (!proto.createShadowRoot) {
+    proto.createShadowRoot = proto.webkitCreateShadowRoot;
+
+    Object.defineProperty(proto, 'shadowRoot', {
+      get: function() {
+        return this.webkitShadowRoot;
+      },
+      set: function(value) {
+        this.webkitShadowRoot = value;
+      },
+      configurable: true
+    });
+  }
 }