*** NOT FOR LANDING *** Avoid localToContainerPoint() in DeprecatedPaintLayerClipper::addClipsFromT…

Source/core/paint/DeprecatedPaintLayerClipper.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 258 matching lines @@
     }
     if (layer->stackingNode()->isStackingContext()) {
         rects.stackingContextClipRects = rects.currentClipRects;
     }
 }
 
 void DeprecatedPaintLayerClipper::addClipsFromThisObject(const ClipRectsContext& context, ClipRects& clipRects) const
 {
     LayoutView* view = m_layoutObject.view();
     ASSERT(view);
+#if 1
+    LayoutPoint offset;
+    m_layoutObject.layer()->convertToLayerCoords(context.rootLayer, offset);
+#else
     // This offset cannot use convertToLayerCoords, because sometimes our rootLayer may be across
     // some transformed layer boundary, for example, in the DeprecatedPaintLayerCompositor overlapMap, where
     // clipRects are needed in view space.
-    LayoutPoint offset = roundedLayoutPoint(m_layoutObject.localToContainerPoint(FloatPoint(), context.rootLayer->layoutObject()));
+    LayoutPoint offset = roundedLayoutPoint(m_layoutObject.localToContainerPoint(FloatPoint(), context.rootLayer->layoutObject())); //
+#endif
     if (clipRects.fixed() && context.rootLayer->layoutObject() == view)
         offset -= toIntSize(view->frameView()->scrollPosition());
 
     // The condition for hasClip here seems wrong. See https://crbug.com/504577
     // (overflowClips can be applied even when shouldRespectOverflowClip returns false)
     if (m_layoutObject.hasOverflowClip() && (shouldRespectOverflowClip(context) || m_layoutObject.hasClip())) {
         ClipRect newOverflowClip = toLayoutBox(m_layoutObject).overflowClipRect(offset, context.scrollbarRelevancy);
         newOverflowClip.setHasRadius(m_layoutObject.style()->hasBorderRadius());
         clipRects.setOverflowClipRect(intersection(newOverflowClip, clipRects.overflowClipRect()));
         if (m_layoutObject.isPositioned())
@@ skipping 164 matching lines @@
     if (context.respectOverflowClip == IgnoreOverflowClip)
         return false;
 
     if (layer->isRootLayer() && context.respectOverflowClipForViewport == IgnoreOverflowClip)
         return false;
 
     return true;
 }
 
 } // namespace blink