Remove mainthread overhang painting code

Source/core/frame/FrameView.h

Index: Source/core/frame/FrameView.h
diff --git a/Source/core/frame/FrameView.h b/Source/core/frame/FrameView.h
index 1a2bcd383df6be561b2025167bc1b455ebeddfd4..1fc10b77291852ba144db88532494a8a0cb1ffc8 100644
--- a/Source/core/frame/FrameView.h
+++ b/Source/core/frame/FrameView.h
@@ -458,8 +458,6 @@ public:
     int scrollX() const { return scrollPosition().x(); }
     int scrollY() const { return scrollPosition().y(); }
 
-    virtual IntSize overhangAmount() const override;
-
     void cacheCurrentScrollPosition() { m_cachedScrollPosition = scrollPositionDouble(); }
     DoublePoint cachedScrollPosition() const { return m_cachedScrollPosition; }
 
@@ -573,8 +571,6 @@ public:
     void notifyPageThatContentAreaWillPaint() const;
     FrameView* parentFrameView() const;
 
-    void calculateOverhangAreasForPainting(IntRect& horizontalOverhangRect, IntRect& verticalOverhangRect);
-
     // Returns the scrollable area for the frame.
     ScrollableArea* scrollableArea();
 
@@ -721,8 +717,6 @@ private:
 
     IntRect rectToCopyOnScroll() const;
 
-    void updateOverhangAreas();
-
     bool isFrameViewScrollbar(const Widget* child) const { return horizontalScrollbar() == child || verticalScrollbar() == child; }
 
     ScrollingCoordinator* scrollingCoordinator();