Remove Internals::createShadowRoot(element) and polyfill.js.

Source/core/testing/Internals.idl

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013 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.
@@ skipping 20 matching lines @@
     [RaisesException] DOMString elementRenderTreeAsText(Element element);
     boolean isPreloaded(DOMString url);
     boolean isLoadingFromMemoryCache(DOMString url);
 
     void crash();
 
     [RaisesException] unsigned long numberOfScopedHTMLStyleChildren(Node scope);
     [RaisesException] CSSStyleDeclaration computedStyleIncludingVisitedInfo(Node node);
 
     [RaisesException] ShadowRoot ensureShadowRoot(Element host);
-    [RaisesException] ShadowRoot createShadowRoot(Element host);
     [RaisesException] ShadowRoot shadowRoot(Element host);
     [RaisesException] ShadowRoot youngestShadowRoot(Element host);
     [RaisesException] ShadowRoot oldestShadowRoot(Element host);
     [RaisesException] ShadowRoot youngerShadowRoot(Node root);
     [RaisesException] ShadowRoot olderShadowRoot(Node root);
 
     [RaisesException] DOMString shadowRootType(Node root);
     [RaisesException] boolean hasShadowInsertionPoint(Node root);
     [RaisesException] boolean hasContentElement(Node root);
     [RaisesException] unsigned long countElementShadow(Node Root);
@@ skipping 191 matching lines @@
     void forceReload(boolean endToEnd);
 
     [Conditional=ENCRYPTED_MEDIA_V2] void initializeMockCDM();
 
     [Conditional=SPEECH_SYNTHESIS] void enableMockSpeechSynthesizer();
 
     [RaisesException] DOMString getImageSourceURL(Element element);
 
     boolean isSelectPopupVisible(Node node);
 };