Bug 902134 - Reduce the number of #includes in nsIDOMWindowUtils.h; r=bzbarsky

dom/interfaces/base/nsIDOMWindowUtils.idl

@@ -15,8 +15,8 @@
 
 %{C++
 #include "nsColor.h"
-#include "nsRect.h"
-#include "gfxContext.h"
+class gfxContext;
+class nsRect;
 %}
 
 [ref] native nsConstRect(const nsRect);