Add clean layout DCHECK to mostBackwardCaretPosition()

third_party/WebKit/Source/core/editing/VisibleSelection.cpp

 /*
  * Copyright (C) 2004, 2005, 2006 Apple Computer, Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 176 matching lines @@
 template <typename Strategy>
 EphemeralRangeTemplate<Strategy>
 VisibleSelectionTemplate<Strategy>::toNormalizedEphemeralRange() const {
   if (isNone())
     return EphemeralRangeTemplate<Strategy>();
 
   // Make sure we have an updated layout since this function is called
   // in the course of running edit commands which modify the DOM.
   // Failing to ensure this can result in equivalentXXXPosition calls returning
   // incorrect results.
-  DCHECK(!m_start.document()->needsLayoutTreeUpdate());
+  DCHECK(!needsLayoutTreeUpdate(m_start)) << *this;
 
   if (isCaret()) {
     // If the selection is a caret, move the range start upstream. This
     // helps us match the conventions of text editors tested, which make
     // style determinations based on the character before the caret, if any.
     const PositionTemplate<Strategy> start =
         mostBackwardCaretPosition(m_start).parentAnchoredEquivalent();
     return EphemeralRangeTemplate<Strategy>(start, start);
   }
   // If the selection is a range, select the minimum range that encompasses
@@ skipping 649 matching lines @@
 
 void showTree(const blink::VisibleSelectionInFlatTree& sel) {
   sel.showTreeForThis();
 }
 
 void showTree(const blink::VisibleSelectionInFlatTree* sel) {
   if (sel)
     sel->showTreeForThis();
 }
 #endif