Make Element::attributes() less error-prone and simplify call sites

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 891 matching lines @@
         const WillBeHeapVector<OwnPtrWillBeMember<HTMLElementEquivalent> >& HTMLElementEquivalents = htmlElementEquivalents();
         size_t i;
         for (i = 0; i < HTMLElementEquivalents.size(); ++i) {
             if (HTMLElementEquivalents[i]->matches(element)) {
                 elementIsSpanOrElementEquivalent = true;
                 break;
             }
         }
     }
 
-    if (!element->hasAttributes())
+    AttributeCollection attributes = element->attributes();
+    if (attributes.isEmpty())
         return elementIsSpanOrElementEquivalent; // span, b, etc... without any attributes
 
     unsigned matchedAttributes = 0;
     const WillBeHeapVector<OwnPtrWillBeMember<HTMLAttributeEquivalent> >& HTMLAttributeEquivalents = htmlAttributeEquivalents();
     for (size_t i = 0; i < HTMLAttributeEquivalents.size(); ++i) {
         if (HTMLAttributeEquivalents[i]->matches(element) && HTMLAttributeEquivalents[i]->attributeName() != HTMLNames::dirAttr)
             matchedAttributes++;
     }
 
     if (!elementIsSpanOrElementEquivalent && !matchedAttributes)
         return false; // element is not a span, a html element equivalent, or font element.
 
     if (element->getAttribute(HTMLNames::classAttr) == AppleStyleSpanClass)
         matchedAttributes++;
 
     if (element->hasAttribute(HTMLNames::styleAttr)) {
         if (const StylePropertySet* style = element->inlineStyle()) {
             unsigned propertyCount = style->propertyCount();
             for (unsigned i = 0; i < propertyCount; ++i) {
                 if (!isEditingProperty(style->propertyAt(i).id()))
                     return false;
             }
         }
         matchedAttributes++;
     }
 
     // font with color attribute, span with style attribute, etc...
-    ASSERT(matchedAttributes <= element->attributes().size());
-    return matchedAttributes >= element->attributes().size();
+    ASSERT(matchedAttributes <= attributes.size());
+    return matchedAttributes >= attributes.size();
 }
 
 void EditingStyle::prepareToApplyAt(const Position& position, ShouldPreserveWritingDirection shouldPreserveWritingDirection)
 {
     if (!m_mutableStyle)
         return;
 
     // ReplaceSelectionCommand::handleStyleSpans() requires that this function only removes the editing style.
     // If this function was modified in the future to delete all redundant properties, then add a boolean value to indicate
     // which one of editingStyleAtPosition or computedStyle is called.
@@ skipping 725 matching lines @@
 {
     for (Node* ancestor = node; ancestor; ancestor = ancestor->parentNode()) {
         RefPtrWillBeRawPtr<CSSComputedStyleDeclaration> ancestorStyle = CSSComputedStyleDeclaration::create(ancestor);
         if (!hasTransparentBackgroundColor(ancestorStyle.get()))
             return ancestorStyle->getPropertyCSSValue(CSSPropertyBackgroundColor);
     }
     return nullptr;
 }
 
 }