Remove mainthread overhang painting code

Source/core/loader/EmptyClients.h

 /*
  * Copyright (C) 2006 Eric Seidel (eric@webkit.org)
  * Copyright (C) 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  * Copyright (C) 2012 Samsung Electronics. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
@@ skipping 134 matching lines @@
     virtual void setCursor(const Cursor&) override { }
 
     virtual void attachRootGraphicsLayer(GraphicsLayer*, LocalFrame* localRoot) override { }
 
     virtual void needTouchEvents(bool) override { }
     virtual void setTouchAction(TouchAction touchAction) override { };
 
     virtual void didAssociateFormControls(const WillBeHeapVector<RefPtrWillBeMember<Element>>&, LocalFrame* frame) override { }
 
     virtual void annotatedRegionsChanged() override { }
-    virtual bool paintCustomOverhangArea(GraphicsContext*, const IntRect&, const IntRect&, const IntRect&) override { return false; }
     virtual String acceptLanguages() override;
 };
 
 class CORE_EXPORT EmptyFrameLoaderClient : public FrameLoaderClient {
     WTF_MAKE_NONCOPYABLE(EmptyFrameLoaderClient); WTF_MAKE_FAST_ALLOCATED(EmptyFrameLoaderClient);
 public:
     EmptyFrameLoaderClient() { }
     virtual ~EmptyFrameLoaderClient() {  }
 
     virtual bool hasWebView() const override { return true; } // mainly for assertions
@@ skipping 142 matching lines @@
     virtual ~EmptyDragClient() {}
     virtual DragDestinationAction actionMaskForDrag(DragData*) override { return DragDestinationActionNone; }
     virtual void startDrag(DragImage*, const IntPoint&, const IntPoint&, DataTransfer*, LocalFrame*, bool) override { }
 };
 
 CORE_EXPORT void fillWithEmptyClients(Page::PageClients&);
 
 }
 
 #endif // EmptyClients_h