Fix pixel snapping issue when transforming

Source/core/layout/Layer.cpp

Index: Source/core/layout/Layer.cpp
diff --git a/Source/core/layout/Layer.cpp b/Source/core/layout/Layer.cpp
index 9cc742b9c67879ea25f09b6ae2821e83c6918222..d7b29c7e9ca57298e19442627cf896666ffc41ff 100644
--- a/Source/core/layout/Layer.cpp
+++ b/Source/core/layout/Layer.cpp
@@ -1627,6 +1627,7 @@ void Layer::collectFragments(LayerFragments& fragments, const Layer* rootLayer,
         ancestorClipRect.intersect(dirtyRect);
     }
 
+    const LayoutSize subPixelAccumulationIfNeeded = compositingState() == PaintsIntoOwnBacking ? LayoutSize() : subPixelAccumulation;
     for (size_t i = 0; i < fragments.size(); ++i) {
         LayerFragment& fragment = fragments.at(i);
 
@@ -1634,7 +1635,7 @@ void Layer::collectFragments(LayerFragments& fragments, const Layer* rootLayer,
         fragment.setRects(layerBoundsInFlowThread, backgroundRectInFlowThread, foregroundRectInFlowThread, outlineRectInFlowThread);
 
         // Shift to the root-relative physical position used when painting the flow thread in this fragment.
-        fragment.moveBy(fragment.paginationOffset + offsetOfPaginationLayerFromRoot);
+        fragment.moveBy(fragment.paginationOffset + offsetOfPaginationLayerFromRoot +  subPixelAccumulationIfNeeded);

[esprehn, 2015/03/24 23:13:23]

extra space

[qiankun, 2015/03/26 11:06:25]

Done.

 
         // Intersect the fragment with our ancestor's background clip so that e.g., columns in an overflow:hidden block are
         // properly clipped by the overflow.