Disable clipping on root scroller's ancestors.

third_party/WebKit/Source/core/paint/PaintLayer.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 143 matching lines @@
     , m_shouldIsolateCompositedDescendants(false)
     , m_lostGroupedMapping(false)
     , m_needsRepaint(false)
     , m_previousPaintResult(PaintLayerPainter::FullyPainted)
     , m_needsPaintPhaseDescendantOutlines(false)
     , m_needsPaintPhaseFloat(false)
     , m_needsPaintPhaseDescendantBlockBackgrounds(false)
     , m_hasDescendantWithClipPath(false)
     , m_hasNonIsolatedDescendantWithBlendMode(false)
     , m_hasAncestorWithClipPath(false)
+    , m_hasRootScrollerAsDescendant(false)
     , m_layoutObject(layoutObject)
     , m_parent(0)
     , m_previous(0)
     , m_next(0)
     , m_first(0)
     , m_last(0)
     , m_staticInlinePosition(0)
     , m_staticBlockPosition(0)
     , m_ancestorOverflowLayer(nullptr)
 {
@@ skipping 796 matching lines @@
 {
     m_ancestorDependentCompositingInputs = compositingInputs;
     if (rareCompositingInputs.isDefault())
         m_rareAncestorDependentCompositingInputs.reset();
     else
         m_rareAncestorDependentCompositingInputs = wrapUnique(new RareAncestorDependentCompositingInputs(rareCompositingInputs));
     m_hasAncestorWithClipPath = hasAncestorWithClipPath;
     m_needsAncestorDependentCompositingInputsUpdate = false;
 }
 
-void PaintLayer::updateDescendantDependentCompositingInputs(bool hasDescendantWithClipPath, bool hasNonIsolatedDescendantWithBlendMode)
+void PaintLayer::updateDescendantDependentCompositingInputs(bool hasDescendantWithClipPath, bool hasNonIsolatedDescendantWithBlendMode, bool hasRootScrollerAsDescendant)
 {
     m_hasDescendantWithClipPath = hasDescendantWithClipPath;
     m_hasNonIsolatedDescendantWithBlendMode = hasNonIsolatedDescendantWithBlendMode;
+    m_hasRootScrollerAsDescendant = hasRootScrollerAsDescendant;
     m_needsDescendantDependentCompositingInputsUpdate = false;
 }
 
 void PaintLayer::didUpdateCompositingInputs()
 {
     ASSERT(!needsCompositingInputsUpdate());
     m_childNeedsCompositingInputsUpdate = false;
     if (m_scrollableArea)
         m_scrollableArea->updateNeedsCompositedScrolling();
 }
@@ skipping 1954 matching lines @@
 
 void showLayerTree(const blink::LayoutObject* layoutObject)
 {
     if (!layoutObject) {
         fprintf(stderr, "Cannot showLayerTree. Root is (nil)\n");
         return;
     }
     showLayerTree(layoutObject->enclosingLayer());
 }
 #endif