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

Source/core/rendering/RenderBlock.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 3796 matching lines @@
 }
 
 bool RenderBlock::hasLineIfEmpty() const
 {
     if (!node())
         return false;
 
     if (node()->isRootEditableElement())
         return true;
 
-    if (node()->isShadowRoot() && toShadowRoot(node())->host()->hasTagName(inputTag))
+    if (node()->isShadowRoot() && isHTMLInputElement(*toShadowRoot(node())->host()))
         return true;
 
     return false;
 }
 
 LayoutUnit RenderBlock::lineHeight(bool firstLine, LineDirectionMode direction, LinePositionMode linePositionMode) const
 {
     // Inline blocks are replaced elements. Otherwise, just pass off to
     // the base class.  If we're being queried as though we're the root line
     // box, then the fact that we're an inline-block is irrelevant, and we behave
@@ skipping 1193 matching lines @@
 void RenderBlock::showLineTreeAndMark(const InlineBox* markedBox1, const char* markedLabel1, const InlineBox* markedBox2, const char* markedLabel2, const RenderObject* obj) const
 {
     showRenderObject();
     for (const RootInlineBox* root = firstRootBox(); root; root = root->nextRootBox())
         root->showLineTreeAndMark(markedBox1, markedLabel1, markedBox2, markedLabel2, obj, 1);
 }
 
 #endif
 
 } // namespace WebCore