Creating custom element should not be case sensitive

Source/core/dom/custom/CustomElementRegistrationContext.cpp

 /*
  * Copyright (C) 2013 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 134 matching lines @@
         return;
     }
 
     // Custom tags take precedence over type extensions
     ASSERT(!CustomElement::isValidName(element->localName()));
 
     if (!CustomElement::isValidName(type))
         return;
 
     element->setCustomElementState(Element::WaitingForUpgrade);
-    context->didGiveTypeExtension(element, type);
+    context->didGiveTypeExtension(element, element->document().convertLocalName(type));
 }
 
 void CustomElementRegistrationContext::trace(Visitor* visitor)
 {
     visitor->trace(m_candidates);
 }
 
 } // namespace blink