Remove some dead code in dom/

Source/core/dom/DOMImplementation.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Samuel Weinig (sam@webkit.org)
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 180 matching lines @@
 PassRefPtr<DocumentType> DOMImplementation::createDocumentType(const AtomicString& qualifiedName,
     const String& publicId, const String& systemId, ExceptionState& exceptionState)
 {
     AtomicString prefix, localName;
     if (!Document::parseQualifiedName(qualifiedName, prefix, localName, exceptionState))
         return nullptr;
 
     return DocumentType::create(&m_document, qualifiedName, publicId, systemId);
 }
 
-DOMImplementation* DOMImplementation::getInterface(const String& /*feature*/)
-{
-    return 0;
-}
-
 PassRefPtr<XMLDocument> DOMImplementation::createDocument(const AtomicString& namespaceURI,
     const AtomicString& qualifiedName, DocumentType* doctype, ExceptionState& exceptionState)
 {
     RefPtr<XMLDocument> doc;
     DocumentInit init = DocumentInit::fromContext(m_document.contextDocument());
     if (namespaceURI == SVGNames::svgNamespaceURI) {
         // FIXME: This should be an XMLDocument as per DOM4 but we need to get rid of SVGDocument first.
         // SVGDocument no longer exists in SVG2.
         doc = SVGDocument::create(init);
     } else if (namespaceURI == HTMLNames::xhtmlNamespaceURI) {
@@ skipping 164 matching lines @@
         return TextDocument::create(init);
     if (type == "image/svg+xml")
         return SVGDocument::create(init);
     if (isXMLMIMEType(type))
         return XMLDocument::create(init);
 
     return HTMLDocument::create(init);
 }
 
 }