Support subpixel layout for borders.

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

Index: third_party/WebKit/Source/core/paint/ThemePainterDefault.cpp
diff --git a/third_party/WebKit/Source/core/paint/ThemePainterDefault.cpp b/third_party/WebKit/Source/core/paint/ThemePainterDefault.cpp
index e0aee2a6ebfd1c19f436551d0c0df8975e607321..6b630db1967eee3c7ad549ea303046e5cc06759c 100644
--- a/third_party/WebKit/Source/core/paint/ThemePainterDefault.cpp
+++ b/third_party/WebKit/Source/core/paint/ThemePainterDefault.cpp
@@ -283,8 +283,8 @@ void ThemePainterDefault::setupMenuListArrow(
     const LayoutBox& box,
     const IntRect& rect,
     WebThemeEngine::ExtraParams& extraParams) {
-  const int left = rect.x() + box.borderLeft();
-  const int right = rect.x() + rect.width() - box.borderRight();
+  const int left = rect.x() + box.borderLeft().toInt();
+  const int right = rect.x() + rect.width() - box.borderRight().toInt();
   const int middle = rect.y() + rect.height() / 2;
 
   extraParams.menuList.arrowY = middle;