Added shim for scrollX and scrollY for IE 9.

tools/dom/templates/html/impl/impl_Window.darttemplate

 // 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.
 
 part of $LIBRARYNAME;
 
 $if DART2JS
 $(ANNOTATIONS)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS native "Window,DOMWindow" {
 $else
 $(ANNOTATIONS)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
@@ skipping 263 matching lines @@
   static const EventStreamProvider<BeforeUnloadEvent> beforeUnloadEvent =
       const _BeforeUnloadEventStreamProvider('beforeunload');
 
   @DomName('Window.onbeforeunload')
   @DocsEditable()
   Stream<Event> get onBeforeUnload => beforeUnloadEvent.forTarget(this);
 
   void moveTo(Point p) {
     $dom_moveTo(p.x, p.y);
   }
+
+$if DART2JS
+  int get scrollX => JS('bool', '("scrollX" in #)', this) ? JS('int', 
+      '#.scrollX', this) : document.documentElement.scrollLeft;
+  int get scrollY => JS('bool', '("scrollY" in #)', this) ? JS('int', 
+      '#.scrollY', this) : document.documentElement.scrollTop;
+$endif
 }
 
 /**
  * Event object that is fired before the window is closed.
  *
  * The standard window close behavior can be prevented by setting the
  * [returnValue]. This will display a dialog to the user confirming that they
  * want to close the page.
  */
 abstract class BeforeUnloadEvent implements Event {
@@ skipping 38 matching lines @@
       return wrapped.returnValue;
     });
 
     return controller.stream;
   }
 
   String getEventType(EventTarget target) {
     return _eventType;
   }
 }