Early-out from the prepaint tree walk

third_party/WebKit/Source/core/paint/PaintLayerClipper.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>
@@ skipping 419 matching lines @@
   return parentRects.overflowClipRect();
 }
 
 ClipRect PaintLayerClipper::clipRectWithGeometryMapper(
     const ClipRectsContext& context,
     bool isForeground) const {
   DCHECK(m_geometryMapper);
   LayoutRect source(LayoutRect::infiniteIntRect());
   bool success = false;
   const auto* properties = m_layer.layoutObject()->paintProperties();
+  DCHECK(properties && properties->localBorderBoxProperties());
   PropertyTreeState propertyTreeState =
       properties->localBorderBoxProperties()->propertyTreeState;
 
   if (isForeground && shouldClipOverflow(context) && properties->overflowClip())
     propertyTreeState.setClip(properties->overflowClip());
 
   const auto* ancestorProperties =
       context.rootLayer->layoutObject()->paintProperties();
+  DCHECK(ancestorProperties && ancestorProperties->localBorderBoxProperties());
   PropertyTreeState destinationPropertyTreeState =
       ancestorProperties->localBorderBoxProperties()->propertyTreeState;
   if (!context.rootLayer->clipper().shouldRespectOverflowClip(context)) {
     if (ancestorProperties->overflowClip())
       destinationPropertyTreeState.setClip(ancestorProperties->overflowClip());
   }
   FloatRect clippedRectInRootLayerSpace =
       m_geometryMapper->mapToVisualRectInDestinationSpace(
           FloatRect(source), propertyTreeState, destinationPropertyTreeState,
           success);
@@ skipping 94 matching lines @@
     const LayoutSize& subpixelAccumulation) const {
   DCHECK(!m_geometryMapper);
   ClipRectsContext context(rootLayer, PaintingClipRects,
                            IgnoreOverlayScrollbarSize, subpixelAccumulation);
   if (respectOverflowClip == IgnoreOverflowClip)
     context.setIgnoreOverflowClip();
   return getClipRects(context);
 }
 
 }  // namespace blink