needsPaintInvalidation() should not return true for selection.

third_party/WebKit/Source/core/layout/LayoutScrollbarPart.cpp

 /*
  * Copyright (C) 2008 Apple 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 193 matching lines @@
 }
 
 void LayoutScrollbarPart::styleDidChange(StyleDifference diff,
                                          const ComputedStyle* oldStyle) {
   LayoutBlock::styleDidChange(diff, oldStyle);
   // See adjustStyleBeforeSet() above.
   ASSERT(!isOrthogonalWritingModeRoot());
   setInline(false);
   clearPositionedState();
   setFloating(false);
-  if (oldStyle && (diff.needsPaintInvalidation() || diff.needsLayout()))
+  if (oldStyle && (diff.needsFullPaintInvalidation() || diff.needsLayout()))
     setNeedsPaintInvalidation();
 }
 
 void LayoutScrollbarPart::imageChanged(WrappedImagePtr image,
                                        const IntRect* rect) {
   setNeedsPaintInvalidation();
   LayoutBlock::imageChanged(image, rect);
 }
 
 LayoutObject* LayoutScrollbarPart::scrollbarStyleSource() const {
@@ skipping 12 matching lines @@
     if (frameView->isFrameViewScrollCorner(this)) {
       frameView->setScrollCornerNeedsPaintInvalidation();
       return;
     }
   }
 
   m_scrollableArea->setScrollCornerNeedsPaintInvalidation();
 }
 
 }  // namespace blink