Remove frameID hack for history.

Source/core/frame/Frame.h

Index: Source/core/frame/Frame.h
diff --git a/Source/core/frame/Frame.h b/Source/core/frame/Frame.h
index 8eda83f61d176803c5ef021edcc440c2a9e7bb9e..36e519bbf74651b7e4ee1a36922a34e82925e9ec 100644
--- a/Source/core/frame/Frame.h
+++ b/Source/core/frame/Frame.h
@@ -82,8 +82,6 @@ public:
 
     RenderPart* ownerRenderer() const; // Renderer for the element that contains this frame.
 
-    int64_t frameID() const { return m_frameID; }
-
     // FIXME: These should move to RemoteFrame when that is instantiated.
     void setRemotePlatformLayer(blink::WebLayer* remotePlatformLayer) { m_remotePlatformLayer = remotePlatformLayer; }
     blink::WebLayer* remotePlatformLayer() const { return m_remotePlatformLayer; }
@@ -108,9 +106,6 @@ private:
 
     HashSet<FrameDestructionObserver*> m_destructionObservers;
 
-    // Temporary hack for history.
-    int64_t m_frameID;
-
     blink::WebLayer* m_remotePlatformLayer;
 };