Refactor reifier to make it less dart_codegen specific.

test/dart_codegen/expect/async/stream_controller.dart

 part of dart.async;
  abstract class StreamController<T> implements StreamSink<T> {Stream<T> get stream;
  factory StreamController({
   void onListen(), void onPause(), void onResume(), onCancel(), bool sync : false}
 ) {
   if (onListen == null && onPause == null && onResume == null && onCancel == null) {
-    return ((__x52) => DEVC$RT.cast(__x52, DEVC$RT.type((_StreamController<dynamic> _) {
+    return ((__x46) => DEVC$RT.cast(__x46, DEVC$RT.type((_StreamController<dynamic> _) {
       }
     ), DEVC$RT.type((StreamController<T> _) {
       }
-    ), "CompositeCast", """line 83, column 14 of dart:async/stream_controller.dart: """, __x52 is StreamController<T>, false))(sync ? new _NoCallbackSyncStreamController() : new _NoCallbackAsyncStreamController());
+    ), "CompositeCast", """line 83, column 14 of dart:async/stream_controller.dart: """, __x46 is StreamController<T>, false))(sync ? new _NoCallbackSyncStreamController() : new _NoCallbackAsyncStreamController());
     }
    return sync ? new _SyncStreamController<T>(onListen, onPause, onResume, onCancel) : new _AsyncStreamController<T>(onListen, onPause, onResume, onCancel);
   }
  factory StreamController.broadcast({
   void onListen(), void onCancel(), bool sync : false}
 ) {
   return sync ? new _SyncBroadcastStreamController<T>(onListen, onCancel) : new _AsyncBroadcastStreamController<T>(onListen, onCancel);
   }
  StreamSink<T> get sink;
  bool get isClosed;
@@ skipping 179 matching lines @@
 _StreamControllerAddStreamState addState = DEVC$RT.cast(_varData, dynamic, DEVC$RT.type((_StreamControllerAddStreamState<dynamic> _) {
   }
 ), "DynamicCast", """line 530, column 50 of dart:async/stream_controller.dart: """, _varData is _StreamControllerAddStreamState<dynamic>, true);
  result = addState.cancel();
 }
  _varData = null;
  _state = (_state & ~(_STATE_SUBSCRIBED | _STATE_ADDSTREAM)) | _STATE_CANCELED;
  if (_onCancel != null) {
 if (result == null) {
   try {
-    result = ((__x53) => DEVC$RT.cast(__x53, dynamic, DEVC$RT.type((Future<dynamic> _) {
+    result = ((__x47) => DEVC$RT.cast(__x47, dynamic, DEVC$RT.type((Future<dynamic> _) {
       }
-    ), "DynamicCast", """line 542, column 20 of dart:async/stream_controller.dart: """, __x53 is Future<dynamic>, true))(_onCancel());
+    ), "DynamicCast", """line 542, column 20 of dart:async/stream_controller.dart: """, __x47 is Future<dynamic>, true))(_onCancel());
     }
    catch (e, s) {
     result = new _Future().._asyncCompleteError(e, s);
     }
   }
  else {
   result = result.whenComplete(_onCancel);
   }
 }
  void complete() {
@@ skipping 115 matching lines @@
 _target.addError(error, stackTrace);
 }
  Future close() => _target.close();
  Future addStream(Stream<T> source, {
 bool cancelOnError : true}
 ) => _target.addStream(source, cancelOnError: cancelOnError);
  Future get done => _target.done;
 }
  class _AddStreamState<T> {final _Future addStreamFuture;
  final StreamSubscription addSubscription;
- _AddStreamState(_EventSink<T> controller, Stream source, bool cancelOnError) : addStreamFuture = new _Future(), addSubscription = source.listen(controller._add, onError: ((__x54) => DEVC$RT.cast(__x54, dynamic, Function, "DynamicCast", """line 746, column 50 of dart:async/stream_controller.dart: """, __x54 is Function, true))(cancelOnError ? makeErrorHandler(controller) : controller._addError), onDone: controller._close, cancelOnError: cancelOnError);
+ _AddStreamState(_EventSink<T> controller, Stream source, bool cancelOnError) : addStreamFuture = new _Future(), addSubscription = source.listen(controller._add, onError: ((__x48) => DEVC$RT.cast(__x48, dynamic, Function, "DynamicCast", """line 746, column 50 of dart:async/stream_controller.dart: """, __x48 is Function, true))(cancelOnError ? makeErrorHandler(controller) : controller._addError), onDone: controller._close, cancelOnError: cancelOnError);
  static makeErrorHandler(_EventSink controller) => (e, StackTrace s) {
 controller._addError(e, s);
  controller._close();
 }
 ;
  void pause() {
 addSubscription.pause();
 }
  void resume() {
 addSubscription.resume();
@@ skipping 17 matching lines @@
  _StreamControllerAddStreamState(_StreamController controller, this.varData, Stream source, bool cancelOnError) : super(DEVC$RT.cast(controller, DEVC$RT.type((_StreamController<dynamic> _) {
 }
 ), DEVC$RT.type((_EventSink<T> _) {
 }
 ), "CompositeCast", """line 798, column 15 of dart:async/stream_controller.dart: """, controller is _EventSink<T>, false), source, cancelOnError) {
 if (controller.isPaused) {
 addSubscription.pause();
 }
 }
 }