Framework for converting embedder uses of WebFrame to WebLocalFrame.

Source/web/WebFrameImpl.h

Index: Source/web/WebFrameImpl.h
diff --git a/Source/web/WebFrameImpl.h b/Source/web/WebFrameImpl.h
index 5ddadee0da30c60e625adeb843e9703015dd65ba..79eec874aa6a62de89664c3d541529c7334f3b72 100644
--- a/Source/web/WebFrameImpl.h
+++ b/Source/web/WebFrameImpl.h
@@ -72,10 +72,11 @@ template <typename T> class WebVector;
 
 // Implementation of WebFrame, note that this is a reference counted object.
 class WebFrameImpl FINAL
-    : public WebFrame
+    : public WebLocalFrame
     , public RefCounted<WebFrameImpl> {
 public:
     // WebFrame methods:
+    virtual WebLocalFrame* toWebLocalFrame() OVERRIDE { return this; }
     virtual void close() OVERRIDE;
     virtual WebString uniqueName() const OVERRIDE;
     virtual WebString assignedName() const OVERRIDE;