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

Source/core/html/HTMLFrameSetElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Simon Hausmann (hausmann@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2006, 2009, 2010 Apple Inc. 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 152 matching lines @@
         return RenderObject::createObject(this, style);
 
     return new RenderFrameSet(this);
 }
 
 void HTMLFrameSetElement::attach(const AttachContext& context)
 {
     // Inherit default settings from parent frameset
     // FIXME: This is not dynamic.
     for (ContainerNode* node = parentNode(); node; node = node->parentNode()) {
-        if (node->hasTagName(framesetTag)) {
-            HTMLFrameSetElement* frameset = toHTMLFrameSetElement(node);
+        if (isHTMLFrameSetElement(*node)) {
+            HTMLFrameSetElement& frameset = toHTMLFrameSetElement(*node);
             if (!m_frameborderSet)
-                m_frameborder = frameset->hasFrameBorder();
+                m_frameborder = frameset.hasFrameBorder();
             if (m_frameborder) {
                 if (!m_borderSet)
-                    m_border = frameset->border();
+                    m_border = frameset.border();
                 if (!m_borderColorSet)
-                    m_borderColorSet = frameset->hasBorderColor();
+                    m_borderColorSet = frameset.hasBorderColor();
             }
             if (!m_noresize)
-                m_noresize = frameset->noResize();
+                m_noresize = frameset.noResize();
             break;
         }
     }
 
     HTMLElement::attach(context);
 }
 
 void HTMLFrameSetElement::defaultEventHandler(Event* evt)
 {
     if (evt->isMouseEvent() && !m_noresize && renderer() && renderer()->isFrameSet()) {
@@ skipping 18 matching lines @@
 {
     if (needsStyleRecalc() && renderer()) {
         renderer()->setNeedsLayout();
         clearNeedsStyleRecalc();
     }
 }
 
 DOMWindow* HTMLFrameSetElement::anonymousNamedGetter(const AtomicString& name)
 {
     Element* frameElement = children()->namedItem(name);
-    if (!frameElement || !frameElement->hasTagName(HTMLNames::frameTag))
+    if (!isHTMLFrameElement(frameElement))
         return 0;
     Document* document = toHTMLFrameElement(frameElement)->contentDocument();
     if (!document || !document->frame())
         return 0;
     return document->domWindow();
 }
 
 } // namespace WebCore