Add @jsify annotation. Support automatically proxying Lists and Maps to Dart in Proxies. Support co…

test_sources/non_transformed/lib/library2.dart

 @Export()
 library test.library2;
 
 import 'package:js/js.dart';
 
 
 abstract class Library2 extends JsInterface {
   factory Library2() => new Library2Impl();
   Library2.created(JsObject o) : super.created(o);
 
   DartOnly createDartOnly();
 
   Gizmo createGizmo(String x);
 
   JsAndDart createJsAndDart(int i);
+
+  List createList(a, b, c);
+
+  String joinList(@jsify List list);
+
+  // The returned object is only a transient wrapper on the underlying JS
+  // object. We might want to make this clear by requiring metadata like
+  // @JsMap. We also might want to support @dartify which would do a deep
+  // copy+convert from JS to Dart
+  Map<String, int> createMap(k1, v1, k2, v2);
+
+  String joinMap(@jsify Map<String, int> map);
 }
 
 @JsProxy(global: true)
 class Library2Impl extends Library2 implements JsGlobal {
   factory Library2Impl() => new JsInterface(Library2Impl, []);
   Library2Impl.created(JsObject o) : super.created(o);
   noSuchMethod(i) => super.noSuchMethod(i);
 }
 
 @NoExport()
@@ skipping 12 matching lines @@
   String get x;
   void set x(String x);
 }
 
 @JsProxy(constructor: 'namespace.Gizmo')
 class GizmoImpl extends Gizmo {
   factory GizmoImpl(String x) => new JsInterface(GizmoImpl, [x]);
   GizmoImpl.created(JsObject o) : super.created(o);
   noSuchMethod(i) => super.noSuchMethod(i);
 }