Add a basic DOMWindow base class and use it in WindowProxy.

Source/core/frame/LocalFrame.cpp

Index: Source/core/frame/LocalFrame.cpp
diff --git a/Source/core/frame/LocalFrame.cpp b/Source/core/frame/LocalFrame.cpp
index 41172b75acca115f17a867c73ce021f6bfa5ec9d..ff443ff96ca1c4c2c1369ea64adf988ef5127043 100644
--- a/Source/core/frame/LocalFrame.cpp
+++ b/Source/core/frame/LocalFrame.cpp
@@ -222,6 +222,7 @@ void LocalFrame::trace(Visitor* visitor)
     visitor->trace(m_loader);
     visitor->trace(m_navigationScheduler);
     visitor->trace(m_view);
+    visitor->trace(m_domWindow);
     visitor->trace(m_pagePopupOwner);
     visitor->trace(m_script);
     visitor->trace(m_editor);
@@ -236,6 +237,11 @@ void LocalFrame::trace(Visitor* visitor)
     Frame::trace(visitor);
 }
 
+LocalDOMWindow* LocalFrame::domWindow() const
+{
+    return m_domWindow.get();
+}
+
 void LocalFrame::navigate(Document& originDocument, const KURL& url, bool lockBackForwardList)
 {
     m_navigationScheduler.scheduleLocationChange(&originDocument, url.string(), lockBackForwardList);
@@ -336,7 +342,10 @@ void LocalFrame::setDOMWindow(PassRefPtrWillBeRawPtr<LocalDOMWindow> domWindow)
     }
     if (domWindow)
         script().clearWindowProxy();
-    Frame::setDOMWindow(domWindow);
+
+    if (m_domWindow)
+        m_domWindow->reset();
+    m_domWindow = domWindow;
 }
 
 Document* LocalFrame::document() const