Adding support for the MouseWheel event in Streams.

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 bbc0d61bfd73d438bb971fdc7a9919c756c32e14..dfbd20e2a4ee12e8197db1d8867128312360aab5 100644
--- a/sdk/lib/html/dartium/html_dartium.dart
+++ b/sdk/lib/html/dartium/html_dartium.dart
@@ -26413,6 +26413,64 @@ class WebSocketEvents extends Events {
 
 /// @domName WheelEvent
 class WheelEvent extends MouseEvent {
+
+  factory WheelEvent(
+      String type,
+      Window view,
+      int wheelDeltaX,
+      int wheelDeltaY,
+      int detail,
+      int screenX,
+      int screenY,
+      int clientX,
+      int clientY,
+      int button,
+      [bool canBubble = true,
+      bool cancelable = true,
+      bool ctrlKey = false,
+      bool altKey = false,
+      bool shiftKey = false,
+      bool metaKey = false,
+      EventTarget relatedTarget = null]) {
+
+    var eventType = 'WheelEvent';
+    if (_Device.isFirefox) {
+      eventType = 'MouseScrollEvents';
+    }
+    final event = document.$dom_createEvent(eventType);
+      // Fallthrough for Dartium.
+      event.$dom_initMouseEvent(
+          type,
+          canBubble,
+          cancelable,
+          view,
+          detail,
+          screenX,
+          screenY,
+          clientX,
+          clientY,
+          ctrlKey,
+          altKey,
+          shiftKey,
+          metaKey,
+          button,
+          relatedTarget);
+      event.$dom_initWebKitWheelEvent(
+          wheelDeltaX,
+          (wheelDeltaY / 120).toInt(), // Chrome does an auto-convert to pixels.
+          view,
+          screenX,
+          screenY,
+          clientX,
+          clientY,
+          ctrlKey,
+          altKey,
+          shiftKey,
+          metaKey);
+
+    return event;
+  }
+
   WheelEvent.internal() : super.internal();
 
 
@@ -26429,7 +26487,7 @@ class WheelEvent extends MouseEvent {
 
 
   /** @domName WheelEvent.initWebKitWheelEvent */
-  void initWebKitWheelEvent(int wheelDeltaX, int wheelDeltaY, Window view, int screenX, int screenY, int clientX, int clientY, bool ctrlKey, bool altKey, bool shiftKey, bool metaKey) native "WheelEvent_initWebKitWheelEvent_Callback";
+  void $dom_initWebKitWheelEvent(int wheelDeltaX, int wheelDeltaY, Window view, int screenX, int screenY, int clientX, int clientY, bool ctrlKey, bool altKey, bool shiftKey, bool metaKey) native "WheelEvent_initWebKitWheelEvent_Callback";
 
 
   /** @domName WheelEvent.deltaX */
@@ -30338,6 +30396,23 @@ class EventStreamProvider<T extends Event> {
     return new _EventStream(e, _eventType, useCapture);
   }
 }
+
+typedef String _EventTypeGetter(EventTarget target);
+
+/**
+ * A factory to expose DOM events as streams, where the DOM event name has to
+ * be determined on the fly (for example, mouse wheel events).
+ */
+class _CustomEventStreamProvider<T extends Event>
+    implements EventStreamProvider<T> {
+
+  final _eventTypeGetter;
+  const _CustomEventStreamProvider(this._eventTypeGetter);
+
+  Stream<T> forTarget(EventTarget e, {bool useCapture: false}) {
+    return new _EventStream(e, _eventTypeGetter(e), useCapture);
+  }
+}
 // Copyright (c) 2012, 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.