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

Source/core/xml/parser/XMLDocumentParser.cpp

 /*
  * Copyright (C) 2000 Peter Kelly (pmk@post.com)
  * Copyright (C) 2005, 2006, 2008, 2014 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2007 Samuel Weinig (sam@webkit.org)
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008 Holger Hans Peter Freyther
  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 794 matching lines @@
         if (!n || !n->isElementNode())
             break;
         parentElement = toElement(n);
     }
 
     if (elemStack.isEmpty())
         return;
 
     for (; !elemStack.isEmpty(); elemStack.removeLast()) {
         Element* element = elemStack.last();
-        if (element->hasAttributes()) {
-            AttributeCollection attributes = element->attributes();
-            AttributeCollection::const_iterator end = attributes.end();
-            for (AttributeCollection::const_iterator it = attributes.begin(); it != end; ++it) {
-                if (it->localName() == xmlnsAtom)
-                    m_defaultNamespaceURI = it->value();
-                else if (it->prefix() == xmlnsAtom)
-                    m_prefixToNamespaceMap.set(it->localName(), it->value());
-            }
+        AttributeCollection attributes = element->attributes();
+        AttributeCollection::const_iterator end = attributes.end();
+        for (AttributeCollection::const_iterator it = attributes.begin(); it != end; ++it) {
+            if (it->localName() == xmlnsAtom)
+                m_defaultNamespaceURI = it->value();
+            else if (it->prefix() == xmlnsAtom)
+                m_prefixToNamespaceMap.set(it->localName(), it->value());
         }
     }
 
     // If the parent element is not in document tree, there may be no xmlns attribute; just default to the parent's namespace.
     if (m_defaultNamespaceURI.isNull() && !parentElement->inDocument())
         m_defaultNamespaceURI = parentElement->namespaceURI();
 }
 
 XMLParserContext::~XMLParserContext()
 {
@@ skipping 797 matching lines @@
     sax.initialized = XML_SAX2_MAGIC;
     RefPtr<XMLParserContext> parser = XMLParserContext::createStringParser(&sax, &state);
     String parseString = "<?xml version=\"1.0\"?><attrs " + string + " />";
     parseChunk(parser->context(), parseString);
     finishParsing(parser->context());
     attrsOK = state.gotAttributes;
     return state.attributes;
 }
 
 } // namespace blink