Run DOM callbacks in the zone they are coming from.

sdk/lib/html/dartium/html_dartium.dart

Index: sdk/lib/html/dartium/html_dartium.dart
diff --git a/sdk/lib/html/dartium/html_dartium.dart b/sdk/lib/html/dartium/html_dartium.dart
index 25a0c3242ad73671264ca3ca6459ec665edee2f3..a597d0c5b474c9289d47738eb7a8f0fb0a33e4f6 100644
--- a/sdk/lib/html/dartium/html_dartium.dart
+++ b/sdk/lib/html/dartium/html_dartium.dart
@@ -30710,11 +30710,17 @@ class _EventStreamSubscription<T extends Event> extends StreamSubscription<T> {
   var _onData;
   final bool _useCapture;
 
-  _EventStreamSubscription(this._target, this._eventType, this._onData,
-      this._useCapture) {
+  _EventStreamSubscription(this._target, this._eventType, onData,
+      this._useCapture) : _onData = _wrapZone(onData) {
     _tryResume();
   }
 
+  static _wrapZone(callback) {
+    // For performance reasons avoid wrapping if we are in the root zone.
+    if (Zone.current == Zone.ROOT) return callback;
+    return Zone.current.bindUnaryCallback(callback);
+  }
+
   void cancel() {
     if (_canceled) return;
 
@@ -30733,7 +30739,7 @@ class _EventStreamSubscription<T extends Event> extends StreamSubscription<T> {
     // Remove current event listener.
     _unlisten();
 
-    _onData = handleData;
+    _onData = _wrapZone(handleData);
     _tryResume();
   }
 
@@ -34729,39 +34735,15 @@ class _Utils {
   static void register(Document document, String tag, Type type,
       String extendsTagName) {
     // TODO(vsm): Move these checks into native code.
-    if (type == null) {
-      throw new UnsupportedError("Invalid null type.");
-    }
     ClassMirror cls = reflectClass(type);
     if (_isBuiltinType(cls)) {
       throw new UnsupportedError("Invalid custom element from $libName.");
     }
-    ClassMirror superClass = cls.superclass;
-
-    Symbol objectName = reflectClass(Object).qualifiedName;
-    bool isRoot(ClassMirror cls) =>
-      cls == null || cls.qualifiedName == objectName;
-    // TODO(vsm): Support extending SvgElement as well.
-    Symbol elementName = reflectClass(HtmlElement).qualifiedName;
-    bool isElement(ClassMirror cls) =>
-      cls != null && cls.qualifiedName == elementName;
-
-    ClassMirror nativeClass = _isBuiltinType(superClass) ? superClass : null;
-    while(!isRoot(superClass) && !isElement(superClass)) {
-      superClass = superClass.superclass;
-      if (nativeClass == null && _isBuiltinType(superClass)) {
-        nativeClass = superClass;
-      }
-    }
-
-    if (isRoot(superClass)) {
-      throw new UnsupportedError("Invalid custom element doesn't inherit from HtmlElement.");
-    }
-    _register(document, tag, type, extendsTagName, nativeClass.reflectedType);
+    _register(document, tag, type, extendsTagName);
   }
 
   static void _register(Document document, String tag, Type customType,
-      String extendsTagName, Type nativeType) native "Utils_register";
+      String extendsTagName) native "Utils_register";
 }
 
 class _NPObject extends NativeFieldWrapperClass1 {