Minimize RenderObject* casting to RenderText*

Source/core/editing/DeleteSelectionCommand.cpp

 /*
  * Copyright (C) 2005 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 21 matching lines @@
 #include "core/dom/NodeTraversal.h"
 #include "core/dom/Text.h"
 #include "core/editing/EditingBoundary.h"
 #include "core/editing/Editor.h"
 #include "core/editing/VisibleUnits.h"
 #include "core/editing/htmlediting.h"
 #include "core/frame/LocalFrame.h"
 #include "core/html/HTMLBRElement.h"
 #include "core/html/HTMLInputElement.h"
 #include "core/rendering/RenderTableCell.h"
+#include "core/rendering/RenderText.h"
 
 namespace blink {
 
 using namespace HTMLNames;
 
 static bool isTableCellEmpty(Node* cell)
 {
     ASSERT(isTableCell(cell));
     return VisiblePosition(firstPositionInNode(cell)) == VisiblePosition(lastPositionInNode(cell));
 }
@@ skipping 833 matching lines @@
     visitor->trace(m_deleteIntoBlockquoteStyle);
     visitor->trace(m_startRoot);
     visitor->trace(m_endRoot);
     visitor->trace(m_startTableRow);
     visitor->trace(m_endTableRow);
     visitor->trace(m_temporaryPlaceholder);
     CompositeEditCommand::trace(visitor);
 }
 
 } // namespace blink