Support JS$ prefix for dart and fix bug where _operator_getter and the [] operator were used incons…

tests/html/simple_dom.dart

+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+@JS("")
+library json_helper;
+
+import 'package:js/js.dart';
+
+// This is a minimal and intentionally hacky raw DOM API built with typed JS
+// interop.
+@JS()
+class EventTarget {
+        external void addEventListener(String type, Function listener, [bool useCapture]);
+        external void removeEventListener(String type, Function listener, [bool useCapture]);
+        external void dispatchEvent(Event event);
+
+        // The dart:html and simple_dom versions of addEventListener are generally
+        // compatible except for behavior capturing this and throwing when passed
+        // event listeners that have not had allowInterop called.
+        external void JS$addEventListener(String type, Function listener, [bool useCapture]);
+        external void JS$removeEventListener(String type, Function listener, [bool useCapture]);
+}
+
+// Example showing addEventListener as a top level memthod
+@JS("document.addEventListener")
+external void documentAddEventListener(String type, Function listener, [bool useCapture]);
+
+@JS()
+@anonymous
+class EventInit {
+        external factory EventInit({bool bubbles, bool cancelable});
+        external bool get bubbles;
+        external bool get cancelable;
+}
+
+@JS()
+class Event {
+        external Event(String type, [EventInit eventInit]);
+        /// This is also defined in dart:html but that is fine as the
+        /// is consistent.
+        external String get type;
+
+        external String get exampleEventExpando;
+        external set exampleEventExpando(String v);
+}
+
+@JS()
+class Window extends EventTarget {
+  external Node get document;
+}
+
+@JS()
+class Node extends EventTarget {
+  external String get textContent;
+
+  external get exampleNodeExpando;
+  external set exampleNodeExpando(v);
+}
+
+@JS()
+class Document extends Node {
+        external Node getElementById(String id);
+}
+
+@JS()
+external Window get window;
+
+@JS()
+external Document get document;