Fix crash when calling ScrollAnchor::clear from PaintLayer's destructor

third_party/WebKit/Source/core/layout/ScrollAnchor.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/layout/ScrollAnchor.h"
 
 #include "core/frame/FrameView.h"
 #include "core/frame/UseCounter.h"
 #include "core/layout/LayoutBlockFlow.h"
 #include "core/layout/api/LayoutBoxItem.h"
@@ skipping 289 matching lines @@
 }
 
 void ScrollAnchor::clearSelf(bool unconditionally) {
   LayoutObject* anchorObject = m_anchorObject;
   m_anchorObject = nullptr;
 
   if (anchorObject)
     anchorObject->clearIsScrollAnchorObject(unconditionally);
 }
 
+void ScrollAnchor::clearSelf() {
+  clearSelf(false);
+}
+
 void ScrollAnchor::clear() {
   LayoutObject* layoutObject =
       m_anchorObject ? m_anchorObject : scrollerLayoutBox(m_scroller);
   PaintLayer* layer = nullptr;
   if (LayoutObject* parent = layoutObject->parent())
     layer = parent->enclosingLayer();
 
   // Walk up the layer tree to clear any scroll anchors.
   while (layer) {
     if (PaintLayerScrollableArea* scrollableArea = layer->getScrollableArea()) {
@@ skipping 14 matching lines @@
 bool ScrollAnchor::refersTo(const LayoutObject* layoutObject) const {
   return m_anchorObject == layoutObject;
 }
 
 void ScrollAnchor::notifyRemoved(LayoutObject* layoutObject) {
   if (m_anchorObject == layoutObject)
     clearSelf();
 }
 
 }  // namespace blink