Fix under-invalidation of frame scrollbar on hover

third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@gmail.com>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 201 matching lines @@
 }
 
 GraphicsLayer* PaintLayerScrollableArea::layerForScrollCorner() const
 {
     // See crbug.com/343132.
     DisableCompositingQueryAsserts disabler;
 
     return layer()->hasCompositedLayerMapping() ? layer()->compositedLayerMapping()->layerForScrollCorner() : 0;
 }
 
-void PaintLayerScrollableArea::scrollControlWasSetNeedsPaintInvalidation()
-{
-    box().setMayNeedPaintInvalidation();
-}
-
 bool PaintLayerScrollableArea::shouldUseIntegerScrollOffset() const
 {
     Frame* frame = box().frame();
     if (frame->settings() && !frame->settings()->preferCompositingToLCDTextEnabled())
         return true;
 
     return ScrollableArea::shouldUseIntegerScrollOffset();
 }
 
 bool PaintLayerScrollableArea::isActive() const
@@ skipping 1516 matching lines @@
 
 void PaintLayerScrollableArea::DelayScrollPositionClampScope::clampScrollableAreas()
 {
     for (auto& scrollableArea : *s_needsClamp)
         scrollableArea->clampScrollPositionsAfterLayout();
     delete s_needsClamp;
     s_needsClamp = nullptr;
 }
 
 } // namespace blink