made GlobalWindowImpl support weak ref to get around

holding on to raw pointers to windows causing problems
in destruction of windows

dom/src/base/nsGlobalWindow.cpp

@@ -171,6 +171,7 @@ NS_INTERFACE_MAP_BEGIN(GlobalWindowImpl)
    NS_INTERFACE_MAP_ENTRY(nsPIDOMWindow)
    NS_INTERFACE_MAP_ENTRY(nsIDOMViewCSS)
    NS_INTERFACE_MAP_ENTRY(nsIDOMAbstractView)
+   NS_INTERFACE_MAP_ENTRY(nsISupportsWeakReference)
 NS_INTERFACE_MAP_END
 
 //*****************************************************************************

dom/src/base/nsGlobalWindow.h

@@ -26,6 +26,7 @@
 // Local Includes
 // Helper Classes
 #include "nsCOMPtr.h"
+#include "nsWeakReference.h"
 #include "nsHashtable.h"
 
 // Interfaces Needed
@@ -78,7 +79,8 @@ class GlobalWindowImpl :   public nsIScriptGlobalObject,
                            public nsIScriptObjectPrincipal,
                            public nsIDOMEventReceiver,
                            public nsPIDOMWindow, 
-                           public nsIDOMViewCSS
+                           public nsIDOMViewCSS,
+                           public nsSupportsWeakReference
 {
 public:
    // nsISupports