Added shim for scrollX and scrollY for IE 9.

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

Index: tools/dom/templates/html/impl/impl_Window.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_Window.darttemplate b/tools/dom/templates/html/impl/impl_Window.darttemplate
index cf2dd3a5d4ba1978336ce7694f873372059e60c5..4c78373acbd2b8834a8ed34fbcdba02983461557 100644
--- a/tools/dom/templates/html/impl/impl_Window.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Window.darttemplate
@@ -281,6 +281,13 @@ $!MEMBERS
   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
 }
 
 /**