Avoid calling hasAttribute() and then getAttribute() for performance

Source/core/editing/SplitElementCommand.cpp

 /*
  * Copyright (C) 2005, 2008 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 75 matching lines @@
     for (Node* node = m_element1->firstChild(); node; node = node->nextSibling())
         children.append(node);
 
     RefPtr<Node> refChild = m_element2->firstChild();
 
     size_t size = children.size();
     for (size_t i = 0; i < size; ++i)
         m_element2->insertBefore(children[i].get(), refChild.get(), IGNORE_EXCEPTION);
 
     // Recover the id attribute of the original element.
-    if (m_element1->hasAttribute(HTMLNames::idAttr))
-        m_element2->setAttribute(HTMLNames::idAttr, m_element1->getAttribute(HTMLNames::idAttr));
+    const AtomicString& id = m_element1->getAttribute(HTMLNames::idAttr);
+    if (!id.isNull())
+        m_element2->setAttribute(HTMLNames::idAttr, id);
 
     m_element1->remove(IGNORE_EXCEPTION);
 }
 
 void SplitElementCommand::doReapply()
 {
     if (!m_element1)
         return;
 
     executeApply();
 }
 
 } // namespace WebCore