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

Source/core/editing/ApplyStyleCommand.cpp

 /*
  * Copyright (C) 2005, 2006, 2008, 2009 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 58 matching lines @@
 
     const HTMLSpanElement& span = toHTMLSpanElement(*node);
     if (span.getAttribute(classAttr) != styleSpanClassString())
         return false;
     UseCounter::count(span.document(), UseCounter::EditingAppleStyleSpanClass);
     return true;
 }
 
 static bool hasNoAttributeOrOnlyStyleAttribute(const HTMLElement* element, ShouldStyleAttributeBeEmpty shouldStyleAttributeBeEmpty)
 {
-    if (!element->hasAttributes())
+    AttributeCollection attributes = element->attributes();
+    if (attributes.isEmpty())
         return true;
 
     unsigned matchedAttributes = 0;
     if (element->getAttribute(classAttr) == styleSpanClassString())
         matchedAttributes++;
     if (element->hasAttribute(styleAttr) && (shouldStyleAttributeBeEmpty == AllowNonEmptyStyleAttribute
         || !element->inlineStyle() || element->inlineStyle()->isEmpty()))
         matchedAttributes++;
 
-    ASSERT(matchedAttributes <= element->attributes().size());
-    return matchedAttributes == element->attributes().size();
+    ASSERT(matchedAttributes <= attributes.size());
+    return matchedAttributes == attributes.size();
 }
 
 bool isStyleSpanOrSpanWithOnlyStyleAttribute(const Element* element)
 {
     if (!isHTMLSpanElement(element))
         return false;
     return hasNoAttributeOrOnlyStyleAttribute(toHTMLSpanElement(element), AllowNonEmptyStyleAttribute);
 }
 
 static inline bool isSpanWithoutAttributesOrUnstyledStyleSpan(const Node* node)
@@ skipping 1470 matching lines @@
 void ApplyStyleCommand::trace(Visitor* visitor)
 {
     visitor->trace(m_style);
     visitor->trace(m_start);
     visitor->trace(m_end);
     visitor->trace(m_styledInlineElement);
     CompositeEditCommand::trace(visitor);
 }
 
 }