Performance fix for high dpi devices.

third_party/WebKit/Source/core/style/ComputedStyle.cpp

 /*
  * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights
  * reserved.
  * Copyright (C) 2011 Adobe Systems Incorporated. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 1498 matching lines @@
       includeLogicalLeftEdge, includeLogicalRightEdge);
 }
 
 FloatRoundedRect ComputedStyle::getRoundedInnerBorderFor(
     const LayoutRect& borderRect,
     const LayoutRectOutsets& insets,
     bool includeLogicalLeftEdge,
     bool includeLogicalRightEdge) const {
   LayoutRect innerRect(borderRect);
   innerRect.expand(insets);
+  innerRect.size().clampNegativeToZero();
 
   FloatRoundedRect roundedRect(pixelSnappedIntRect(innerRect));
 
   if (hasBorderRadius()) {
     FloatRoundedRect::Radii radii = getRoundedBorderFor(borderRect).getRadii();
     // Insets use negative values.
     radii.shrink(-insets.top().toFloat(), -insets.bottom().toFloat(),
                  -insets.left().toFloat(), -insets.right().toFloat());
     roundedRect.includeLogicalEdges(radii, isHorizontalWritingMode(),
                                     includeLogicalLeftEdge,
@@ skipping 973 matching lines @@
     if (value < 0)
       fvalue -= 0.5f;
     else
       fvalue += 0.5f;
   }
 
   return roundForImpreciseConversion<int>(fvalue / zoomFactor);
 }
 
 }  // namespace blink