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/CustomEvent.webidl

@@ -0,0 +1,33 @@
+/* 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/. */
+/*
+ * For more information on this interface please see
+ * https://dom.spec.whatwg.org/#interface-customevent
+ *
+ * To the extent possible under law, the editors have waived
+ * all copyright and related or neighboring rights to this work.
+ * In addition, as of 1 May 2014, the editors have made this specification
+ * available under the Open Web Foundation Agreement Version 1.0,
+ * which is available at
+ * http://www.openwebfoundation.org/legal/the-owf-1-0-agreements/owfa-1-0.
+ */
+
+// https://dom.spec.whatwg.org/#dom-customevent-initcustomevent
+[Exposed=*]
+interface CustomEvent : Event {
+  constructor(DOMString type, optional CustomEventInit eventInitDict = {});
+
+  readonly attribute any detail;
+
+  undefined initCustomEvent(
+    DOMString type,
+    optional boolean bubbles = false,
+    optional boolean cancelable = false,
+    optional any detail = null
+  ); // legacy
+};
+
+dictionary CustomEventInit : EventInit {
+  any detail = null;
+};