Remove ENABLE_CUSTOM_ELEMENTS compile time flag

Source/core/dom/CustomElementConstructor.h

 /*
  * Copyright (C) 2012 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 13 matching lines @@
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef CustomElementConstructor_h
 #define CustomElementConstructor_h
 
-#if ENABLE(CUSTOM_ELEMENTS)
-
 #include "ContextDestructionObserver.h"
 #include "Document.h"
 #include "QualifiedName.h"
 #include <wtf/Forward.h>
 #include <wtf/PassRefPtr.h>
 #include <wtf/RefCounted.h>
 #include <wtf/text/AtomicString.h>
 
 namespace WebCore {
 
@@ skipping 21 matching lines @@
     CustomElementConstructor(Document*, const QualifiedName& typeName, const QualifiedName& localName);
 
     PassRefPtr<Element> createElementInternal();
 
     QualifiedName m_typeName;
     QualifiedName m_localName;
 };
 
 }
 
-#endif // ENABLE(CUSTOM_ELEMENTS)
-
 #endif // CustomElementConstructor_h