Auto merge of #9407 - KiChjang:radio-node-list, r=nox

Implement RadioNodeList

I also had to implement the NamedGetter for HTMLFormControlsCollection as well, since that's the only consumer of RadioNodeList and I wanted to see which wpt test passes.

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components/script/dom/webidls/HTMLFormControlsCollection.webidl

@@ -6,11 +6,5 @@
 // https://html.spec.whatwg.org/multipage/#htmlformcontrolscollection
 interface HTMLFormControlsCollection : HTMLCollection {
   // inherits length and item()
-  // getter (RadioNodeList or Element)? namedItem(DOMString name); // shadows inherited namedItem()
+  getter (RadioNodeList or Element)? namedItem(DOMString name); // shadows inherited namedItem()
 };
-
-/*
-interface RadioNodeList : NodeList {
-  attribute DOMString value;
-};
-*/

components/script/dom/webidls/NodeList.webidl

@@ -8,8 +8,9 @@
  */
 
 interface NodeList {
-  [Pure]
-  readonly attribute unsigned long length;
   [Pure]
   getter Node? item(unsigned long index);
+  [Pure]
+  readonly attribute unsigned long length;
+  // iterable<Node>;
 };

components/script/dom/webidls/RadioNodeList.webidl

@@ -0,0 +1,9 @@
+/* -*- 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/. */
+
+// https://html.spec.whatwg.org/multipage/#radionodelist
+interface RadioNodeList : NodeList {
+  attribute DOMString value;
+};