Support subpixel layout for borders.

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/paint/NinePieceImageGrid.h"
 
 #include "core/style/ComputedStyle.h"
 #include "core/style/NinePieceImage.h"
 #include "platform/LengthFunctions.h"
 #include "platform/geometry/FloatSize.h"
 #include "platform/geometry/IntSize.h"
 
 namespace blink {
 
 static int computeEdgeWidth(const BorderImageLength& borderSlice,
                             int borderSide,
                             int imageSide,
                             int boxExtent) {
   if (borderSlice.isNumber())
-    return borderSlice.number() * borderSide;
+    return roundf(borderSlice.number() * borderSide);
   if (borderSlice.length().isAuto())
     return imageSide;
-  return valueForLength(borderSlice.length(), LayoutUnit(boxExtent)).toInt();
+  return valueForLength(borderSlice.length(), LayoutUnit(boxExtent)).round();
 }
 
 static int computeEdgeSlice(const Length& slice, int maximum) {
   return std::min<int>(maximum,
-                       valueForLength(slice, LayoutUnit(maximum)).toInt());
+                       valueForLength(slice, LayoutUnit(maximum)).round());
 }
 
 NinePieceImageGrid::NinePieceImageGrid(const NinePieceImage& ninePieceImage,
                                        IntSize imageSize,
                                        IntRect borderImageArea,
                                        const IntRectOutsets& borderWidths)
     : m_borderImageArea(borderImageArea),
       m_imageSize(imageSize),
       m_horizontalTileRule((Image::TileRule)ninePieceImage.horizontalRule()),
       m_verticalTileRule((Image::TileRule)ninePieceImage.verticalRule()),
@@ skipping 261 matching lines @@
     drawInfo.source.scale(imageScaleFactor);
 
     // Compensate for source scaling by scaling down the individual tiles.
     drawInfo.tileScale.scale(1 / imageScaleFactor);
   }
 
   return drawInfo;
 }
 
 }  // namespace blink