Remove the redundant layout update from WebSurroundingText::textContent

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

 /*
  * Copyright (C) 2012 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 86 matching lines @@
           .length();
   m_endOffsetInContent =
       Range::create(*document, backwardsIterator.endPosition(), endPosition)
           ->text()
           .length();
   m_contentRange = Range::create(*document, backwardsIterator.endPosition(),
                                  forwardRange.startPosition());
   DCHECK(m_contentRange);
 }
 
-Document* SurroundingText::document() const {
-  if (m_contentRange)
-    return &m_contentRange->ownerDocument();
-  return nullptr;
-}
-
 String SurroundingText::content() const {
-  if (m_contentRange)
+  if (m_contentRange) {
+    // SurroundingText is created with clean layout and must not be stored
+    // through DOM or style changes, so layout must still be clean here.
+    DCHECK(!m_contentRange->ownerDocument().needsLayoutTreeUpdate());
     return m_contentRange->text();
+  }
   return String();
 }
 
 unsigned SurroundingText::startOffsetInContent() const {
   return m_startOffsetInContent;
 }
 
 unsigned SurroundingText::endOffsetInContent() const {
   return m_endOffsetInContent;
 }
 
 }  // namespace blink