Use new is*Element() helper functions more in editing code

Source/core/editing/TypingCommand.cpp

 /*
  * Copyright (C) 2005, 2006, 2007, 2008 Apple 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 23 matching lines @@
 #include "core/editing/Editor.h"
 #include "core/editing/FrameSelection.h"
 #include "core/editing/InsertLineBreakCommand.h"
 #include "core/editing/InsertParagraphSeparatorCommand.h"
 #include "core/editing/InsertTextCommand.h"
 #include "core/editing/SpellChecker.h"
 #include "core/editing/VisiblePosition.h"
 #include "core/editing/VisibleUnits.h"
 #include "core/editing/htmlediting.h"
 #include "core/frame/LocalFrame.h"
+#include "core/html/HTMLBRElement.h"
 #include "core/rendering/RenderObject.h"
 
 namespace WebCore {
 
 using namespace HTMLNames;
 
 class TypingCommandLineOperation
 {
 public:
     TypingCommandLineOperation(TypingCommand* typingCommand, bool selectInsertedText, const String& text)
@@ skipping 323 matching lines @@
 }
 
 bool TypingCommand::makeEditableRootEmpty()
 {
     Element* root = endingSelection().rootEditableElement();
     if (!root || !root->firstChild())
         return false;
 
     if (root->firstChild() == root->lastChild()) {
         Element* firstElementChild = ElementTraversal::firstWithin(*root);
-        if (firstElementChild && firstElementChild->hasTagName(brTag)) {
+        if (isHTMLBRElement(firstElementChild)) {
             // If there is a single child and it could be a placeholder, leave it alone.
             if (root->renderer() && root->renderer()->isRenderBlockFlow())
                 return false;
         }
     }
 
     while (Node* child = root->firstChild())
         removeNode(child);
 
     addBlockPlaceholderIfNeeded(root);
@@ skipping 220 matching lines @@
     ASSERT_NOT_REACHED();
     m_preservesTypingStyle = false;
 }
 
 bool TypingCommand::isTypingCommand() const
 {
     return true;
 }
 
 } // namespace WebCore