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..7af28fa4af6053c648c465e552bf93f94f51e632 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('int', 
+      '#.scrollX || document.documentElement.scrollLeft', this);

[blois, 2013/07/26 00:36:23]

should use:
=> JS('bool', '("scrollX" in #)', this) ? this.scrollX :
document.documentElement.scrollLeft;

This way a value of zero will still return window.scrollX rather than
document.documentElement.scrollLeft.

+  int get scrollY => JS('int', 
+      '#.scrollY || document.documentElement.scrollTop', this);
+$endif
 }
 
 /**