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

LayoutTests/fast/dom/shadow/resources/shadow-dom.js

 function createShadowRoot()
 {
     return {'isShadowRoot': true,
             'children': Array.prototype.slice.call(arguments)};
 }
 
 function createShadowRootWithAttributes(attributes, children)
 {
     return {'isShadowRoot': true,
             'attributes': attributes,
             'children': children};
 }
 
 // This function can take optional child elements, which might be a result of createShadowRoot(), as arguments[2:].
 // You must enable SHADOW_DOM flag if you use this fucntion to host multiple ShadowRoots
 // since window.internals does not have a function which can be used to host multiple shadow roots.
 // FIXME: window.internals should have such function and remove the restriction.
 function createDOM(tagName, attributes)
 {
     var element = document.createElement(tagName);
     for (var name in attributes)
         element.setAttribute(name, attributes[name]);
     var childElements = Array.prototype.slice.call(arguments, 2);
     var shadowRootCount = 0;
     for (var i = 0; i < childElements.length; ++i) {
         var child = childElements[i];
         if (child.isShadowRoot) {
             ++shadowRootCount;
-            var shadowRoot;
-            if (element.webkitCreateShadowRoot)
-                shadowRoot = element.webkitCreateShadowRoot(element);
-            else
-                shadowRoot = internals.createShadowRoot(element);
+            var shadowRoot = element.webkitCreateShadowRoot(element);
             if (child.attributes) {
                 for (var attribute in child.attributes) {
                     // Shadow Root does not have setAttribute.
                     shadowRoot[attribute] = child.attributes[attribute];
                 }
             }
             for (var j = 0; j < child.children.length; ++j)
                 shadowRoot.appendChild(child.children[j]);
         } else
             element.appendChild(child);
@@ skipping 118 matching lines @@
 {
     for (var i = 0; i + 1 < elements.length; ++i)
         shouldNavigateFocus(elements[i], elements[i + 1], 'forward');
 }
 
 function testFocusNavigationBackward(elements)
 {
     for (var i = 0; i + 1 < elements.length; ++i)
         shouldNavigateFocus(elements[i], elements[i + 1], 'backward');
 }