Fix pixel snapping issue when transforming

Source/core/paint/LayerPainter.cpp

Index: Source/core/paint/LayerPainter.cpp
diff --git a/Source/core/paint/LayerPainter.cpp b/Source/core/paint/LayerPainter.cpp
index 80da3d5d156e35e0624b561eb964185d527b3640..10d1738e24c34e6ca5fcd4abd30bf20edde5312e 100644
--- a/Source/core/paint/LayerPainter.cpp
+++ b/Source/core/paint/LayerPainter.cpp
@@ -196,6 +196,8 @@ void LayerPainter::paintLayerContents(GraphicsContext* context, const LayerPaint
 
     if (m_renderLayer.compositingState() == PaintsIntoOwnBacking)
         offsetFromRoot.move(m_renderLayer.subpixelAccumulation());
+    else
+        offsetFromRoot.move(paintingInfo.subPixelAccumulation);
 
     LayoutRect rootRelativeBounds;
     bool rootRelativeBoundsComputed = false;
@@ -442,15 +444,6 @@ bool LayerPainter::shouldPaintLayerInSoftwareMode(const LayerPaintingInfo& paint
         || paintForFixedRootBackground(&m_renderLayer, paintFlags);
 }
 
-static inline LayoutSize subPixelAccumulationIfNeeded(const LayoutSize& subPixelAccumulation, CompositingState compositingState)
-{
-    // Only apply the sub-pixel accumulation if we don't paint into our own backing layer, otherwise the position
-    // of the renderer already includes any sub-pixel offset.
-    if (compositingState == PaintsIntoOwnBacking)
-        return LayoutSize();
-    return subPixelAccumulation;
-}
-
 void LayerPainter::paintOverflowControlsForFragments(const LayerFragments& layerFragments, GraphicsContext* context, const LayerPaintingInfo& localPaintingInfo, PaintLayerFlags paintFlags)
 {
     for (size_t i = 0; i < layerFragments.size(); ++i) {
@@ -463,7 +456,7 @@ void LayerPainter::paintOverflowControlsForFragments(const LayerFragments& layer
             clipRecorder = adoptPtr(new LayerClipRecorder(m_renderLayer.renderer(), context, DisplayItem::ClipLayerOverflowControls, fragment.backgroundRect, &localPaintingInfo, fragment.paginationOffset, paintFlags));
         }
         if (LayerScrollableArea* scrollableArea = m_renderLayer.scrollableArea())
-            ScrollableAreaPainter(*scrollableArea).paintOverflowControls(context, roundedIntPoint(toPoint(fragment.layerBounds.location() - m_renderLayer.layoutBoxLocation() + subPixelAccumulationIfNeeded(localPaintingInfo.subPixelAccumulation, m_renderLayer.compositingState()))), pixelSnappedIntRect(fragment.backgroundRect.rect()), true);
+            ScrollableAreaPainter(*scrollableArea).paintOverflowControls(context, roundedIntPoint(toPoint(fragment.layerBounds.location() - m_renderLayer.layoutBoxLocation())), pixelSnappedIntRect(fragment.backgroundRect.rect()), true);
     }
 }
 
@@ -625,7 +618,7 @@ void LayerPainter::paintFragmentWithPhase(PaintPhase phase, const LayerFragment&
     }
 
     PaintInfo paintInfo(context, pixelSnappedIntRect(clipRect.rect()), phase, paintBehavior, paintingRootForRenderer, 0, paintingInfo.rootLayer->renderer());
-    m_renderLayer.renderer()->paint(paintInfo, toPoint(fragment.layerBounds.location() - m_renderLayer.layoutBoxLocation() + subPixelAccumulationIfNeeded(paintingInfo.subPixelAccumulation, m_renderLayer.compositingState())));
+    m_renderLayer.renderer()->paint(paintInfo, toPoint(fragment.layerBounds.location() - m_renderLayer.layoutBoxLocation()));
 }
 
 void LayerPainter::paintBackgroundForFragments(const LayerFragments& layerFragments, GraphicsContext* context,