Add DOMImplementation skeleton

Creates a DOMImplementation struct corresponding to DOMImplementation
WebIDL. Also implements a getter for Document::implementation.

Closes #1486.

src/components/script/dom/bindings/codegen/Bindings.conf

@@ -160,6 +160,10 @@ DOMInterfaces = {
     ],
 },
 
+'DOMImplementation': {
+    'nativeType': 'DOMImplementation',
+},
+
 'DOMParser': {
     'nativeType': 'DOMParser',
 },

src/components/script/dom/bindings/codegen/DOMImplementation.webidl

@@ -0,0 +1,26 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * The origin of this IDL file is
+ * http://dom.spec.whatwg.org/#interface-domimplementation
+ *
+ * Copyright:
+ * To the extent possible under law, the editors have waived all copyright and
+ * related or neighboring rights to this work.
+ */
+
+interface DOMImplementation {
+  /*boolean hasFeature(DOMString feature,
+                     [TreatNullAs=EmptyString] DOMString version);*/
+  /*[Throws]
+  DocumentType createDocumentType(DOMString qualifiedName, DOMString publicId,
+                                  DOMString systemId);*/
+  /*[Throws]
+  Document createDocument(DOMString? namespace,
+                          [TreatNullAs=EmptyString] DOMString qualifiedName,
+                          optional DocumentType? doctype = null);*/
+  /*[Throws]
+  Document createHTMLDocument(optional DOMString title);*/
+};

src/components/script/dom/bindings/codegen/Document.webidl

@@ -25,8 +25,7 @@ enum VisibilityState { "hidden", "visible" };
 /* http://dom.spec.whatwg.org/#interface-document */
 [Constructor]
 interface Document : Node {
-  /*[Throws]
-    readonly attribute DOMImplementation implementation;*/
+  readonly attribute DOMImplementation implementation;
   // readonly attribute DOMString URL;
   // readonly attribute DOMString documentURI;
   // readonly attribute DOMString compatMode;