Remove mainthread overhang painting code

Source/web/tests/ScrollAnimatorNoneTest.cpp

 /*
  * Copyright (C) 2010 Google Inc. 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
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 44 matching lines @@
     MOCK_CONST_METHOD0(scrollCornerRect, IntRect());
     MOCK_METHOD1(setScrollOffset, void(const IntPoint&));
     MOCK_METHOD2(invalidateScrollbarRect, void(Scrollbar*, const IntRect&));
     MOCK_METHOD1(invalidateScrollCornerRect, void(const IntRect&));
     MOCK_METHOD1(setScrollOffsetFromAnimation, void(const IntPoint&));
     MOCK_CONST_METHOD0(enclosingScrollableArea, ScrollableArea*());
     MOCK_CONST_METHOD0(minimumScrollPosition, IntPoint());
     MOCK_CONST_METHOD0(maximumScrollPosition, IntPoint());
     MOCK_CONST_METHOD1(visibleContentRect, IntRect(IncludeScrollbarsInRect));
     MOCK_CONST_METHOD0(contentsSize, IntSize());
-    MOCK_CONST_METHOD0(overhangAmount, IntSize());
     MOCK_CONST_METHOD0(scrollbarsCanBeActive, bool());
     MOCK_CONST_METHOD0(scrollableAreaBoundingBox, IntRect());
 
     virtual bool userInputScrollable(ScrollbarOrientation) const override { return true; }
     virtual bool shouldPlaceVerticalScrollbarOnLeft() const override { return false; }
     virtual IntPoint scrollPosition() const override { return IntPoint(); }
     virtual int visibleHeight() const override { return 768; }
     virtual int visibleWidth() const override { return 1024; }
     virtual bool scrollAnimatorEnabled() const override { return m_scrollAnimatorEnabled; }
     virtual int pageStep(ScrollbarOrientation) const override { return 0; }
@@ skipping 973 matching lines @@
     EXPECT_TRUE(result);
     result = result && animateScroll(t);
     double after = m_currentPosition;
     EXPECT_GE(before, after);
 
     t += kAnimationTime;
     for (; result && t < kEndTime; t += kAnimationTime)
         result = result && animateScroll(t);
     EXPECT_GE(before, m_currentPosition);
 }