script: Move code generation and webidl files to new script_bindings crate. (#35157)

Signed-off-by: Josh Matthews <josh@joshmatthews.net>

components/script_bindings/webidls/HTMLCollection.webidl

@@ -0,0 +1,15 @@
+/* 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 https://mozilla.org/MPL/2.0/. */
+
+// https://dom.spec.whatwg.org/#interface-htmlcollection
+
+[Exposed=Window, LegacyUnenumerableNamedProperties]
+interface HTMLCollection {
+  [Pure]
+  readonly attribute unsigned long length;
+  [Pure]
+  getter Element? item(unsigned long index);
+  [Pure]
+  getter Element? namedItem(DOMString name);
+};