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

Source/core/editing/EditingStyle.cpp

 /*
  * Copyright (C) 2007, 2008, 2009 Apple Computer, Inc.
  * Copyright (C) 2010, 2011 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:
  * 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
@@ skipping 863 matching lines @@
     return removed;
 }
 
 bool EditingStyle::styleIsPresentInComputedStyleOfNode(Node* node) const
 {
     return !m_mutableStyle || getPropertiesNotIn(m_mutableStyle.get(), CSSComputedStyleDeclaration::create(node).get())->isEmpty();
 }
 
 bool EditingStyle::elementIsStyledSpanOrHTMLEquivalent(const HTMLElement* element)
 {
+    ASSERT(element);
     bool elementIsSpanOrElementEquivalent = false;
-    if (element->hasTagName(HTMLNames::spanTag))
+    if (isHTMLSpanElement(*element))
         elementIsSpanOrElementEquivalent = true;
     else {
         const Vector<OwnPtr<HTMLElementEquivalent> >& HTMLElementEquivalents = htmlElementEquivalents();
         size_t i;
         for (i = 0; i < HTMLElementEquivalents.size(); ++i) {
             if (HTMLElementEquivalents[i]->matches(element)) {
                 elementIsSpanOrElementEquivalent = true;
                 break;
             }
         }
@@ skipping 737 matching lines @@
 {
     for (Node* ancestor = node; ancestor; ancestor = ancestor->parentNode()) {
         RefPtr<CSSComputedStyleDeclaration> ancestorStyle = CSSComputedStyleDeclaration::create(ancestor);
         if (!hasTransparentBackgroundColor(ancestorStyle.get()))
             return ancestorStyle->getPropertyCSSValue(CSSPropertyBackgroundColor);
     }
     return nullptr;
 }
 
 }