Rationalize coercions

test/dart_codegen/expect/async/stream_impl.dart

 part of dart.async;
  abstract class _EventSink<T> {void _add(T data);
  void _addError(Object error, StackTrace stackTrace);
  void _close();
 }
  abstract class _EventDispatch<T> {void _sendData(T data);
  void _sendError(Object error, StackTrace stackTrace);
  void _sendDone();
 }
  class _BufferingStreamSubscription<T> implements StreamSubscription<T>, _EventSink<T>, _EventDispatch<T> {static const int _STATE_CANCEL_ON_ERROR = 1;
@@ skipping 82 matching lines @@
  return _cancelFuture;
 }
  Future asFuture([var futureValue]) {
 _Future<T> result = new _Future<T>();
  _onDone = () {
 result._complete(futureValue);
 }
 ;
  _onError = (error, stackTrace) {
 cancel();
- result._completeError(error, DEVC$RT.cast(stackTrace, dynamic, StackTrace, "CastGeneral", """line 212, column 36 of dart:async/stream_impl.dart: """, stackTrace is StackTrace, true));
+ result._completeError(error, DEVC$RT.cast(stackTrace, dynamic, StackTrace, "DynamicCast", """line 212, column 36 of dart:async/stream_impl.dart: """, stackTrace is StackTrace, true));
 }
 ;
  return result;
 }
  bool get _isInputPaused => (_state & _STATE_INPUT_PAUSED) != 0;
  bool get _isClosed => (_state & _STATE_CLOSED) != 0;
  bool get _isCanceled => (_state & _STATE_CANCELED) != 0;
  bool get _waitsForCancel => (_state & _STATE_WAIT_FOR_CANCEL) != 0;
  bool get _inCallback => (_state & _STATE_IN_CALLBACK) != 0;
  bool get _hasPending => (_state & _STATE_HAS_PENDING) != 0;
@@ skipping 42 matching lines @@
 }
 }
  void _onPause() {
 assert (_isInputPaused);}
  void _onResume() {
 assert (!_isInputPaused);}
  Future _onCancel() {
 assert (_isCanceled); return null;
 }
  void _addPending(_DelayedEvent event) {
-_StreamImplEvents pending = DEVC$RT.cast(_pending, _PendingEvents, _StreamImplEvents, "CastGeneral", """line 322, column 33 of dart:async/stream_impl.dart: """, _pending is _StreamImplEvents, true);
+_StreamImplEvents pending = DEVC$RT.cast(_pending, _PendingEvents, _StreamImplEvents, "AssignmentCast", """line 322, column 33 of dart:async/stream_impl.dart: """, _pending is _StreamImplEvents, true);
  if (_pending == null) pending = _pending = new _StreamImplEvents();
  pending.add(event);
  if (!_hasPending) {
 _state |= _STATE_HAS_PENDING;
  if (!_isPaused) {
   _pending.schedule(this);
   }
 }
 }
  void _sendData(T data) {
 assert (!_isCanceled); assert (!_isPaused); assert (!_inCallback); bool wasInputPaused = _isInputPaused;
  _state |= _STATE_IN_CALLBACK;
  _zone.runUnaryGuarded(_onData, data);
  _state &= ~_STATE_IN_CALLBACK;
  _checkState(wasInputPaused);
 }
  void _sendError(var error, StackTrace stackTrace) {
 assert (!_isCanceled); assert (!_isPaused); assert (!_inCallback); bool wasInputPaused = _isInputPaused;
  void sendError() {
 if (_isCanceled && !_waitsForCancel) return; _state |= _STATE_IN_CALLBACK;
  if (_onError is ZoneBinaryCallback) {
-  _zone.runBinaryGuarded(DEVC$RT.cast(_onError, Function, __t95, "CastGeneral", """line 358, column 32 of dart:async/stream_impl.dart: """, _onError is __t95, true), error, stackTrace);
+  _zone.runBinaryGuarded(DEVC$RT.cast(_onError, Function, __t95, "ImplicitCast", """line 358, column 32 of dart:async/stream_impl.dart: """, _onError is __t95, true), error, stackTrace);
   }
  else {
-  _zone.runUnaryGuarded(DEVC$RT.cast(_onError, Function, __t92, "CastGeneral", """line 360, column 31 of dart:async/stream_impl.dart: """, _onError is __t92, true), error);
+  _zone.runUnaryGuarded(DEVC$RT.cast(_onError, Function, __t92, "ImplicitCast", """line 360, column 31 of dart:async/stream_impl.dart: """, _onError is __t92, true), error);
   }
  _state &= ~_STATE_IN_CALLBACK;
 }
  if (_cancelOnError) {
 _state |= _STATE_WAIT_FOR_CANCEL;
  _cancel();
  if (_cancelFuture is Future) {
   _cancelFuture.whenComplete(sendError);
   }
  else {
@@ skipping 58 matching lines @@
  abstract class _StreamImpl<T> extends Stream<T> {StreamSubscription<T> listen(void onData(T data), {
 Function onError, void onDone(), bool cancelOnError}
 ) {
 cancelOnError = identical(true, cancelOnError);
  StreamSubscription subscription = _createSubscription(onData, onError, onDone, cancelOnError);
  _onListen(subscription);
  return DEVC$RT.cast(subscription, DEVC$RT.type((StreamSubscription<dynamic> _) {
 }
 ), DEVC$RT.type((StreamSubscription<T> _) {
 }
-), "CastDynamic", """line 476, column 12 of dart:async/stream_impl.dart: """, subscription is StreamSubscription<T>, false);
+), "CompositeCast", """line 476, column 12 of dart:async/stream_impl.dart: """, subscription is StreamSubscription<T>, false);
 }
  _BufferingStreamSubscription<T> _createSubscription(void onData(T data), Function onError, void onDone(), bool cancelOnError) {
 return new _BufferingStreamSubscription<T>(onData, onError, onDone, cancelOnError);
 }
  void _onListen(StreamSubscription subscription) {
 }
 }
  typedef _PendingEvents _EventGenerator();
  class _GeneratedStreamImpl<T> extends _StreamImpl<T> {final _EventGenerator _pending;
  bool _isUsed = false;
@@ skipping 293 matching lines @@
 }
  if (_state == _STATE_MOVING) {
 throw new StateError("Already waiting for next.");
 }
  if (_state == _STATE_FOUND) {
 _state = _STATE_MOVING;
  _current = null;
  _futureOrPrefetch = new _Future<bool>();
  return DEVC$RT.cast(_futureOrPrefetch, dynamic, DEVC$RT.type((Future<bool> _) {
 }
-), "CastGeneral", """line 1000, column 14 of dart:async/stream_impl.dart: """, _futureOrPrefetch is Future<bool>, false);
+), "CompositeCast", """line 1000, column 14 of dart:async/stream_impl.dart: """, _futureOrPrefetch is Future<bool>, false);
 }
  else {
 assert (_state >= _STATE_EXTRA_DATA); switch (_state) {case _STATE_EXTRA_DATA: _state = _STATE_FOUND;
- _current = DEVC$RT.cast(_futureOrPrefetch, dynamic, T, "CastGeneral", """line 1006, column 22 of dart:async/stream_impl.dart: """, _futureOrPrefetch is T, false);
+ _current = DEVC$RT.cast(_futureOrPrefetch, dynamic, T, "CompositeCast", """line 1006, column 22 of dart:async/stream_impl.dart: """, _futureOrPrefetch is T, false);
  _futureOrPrefetch = null;
  _subscription.resume();
  return new _Future<bool>.immediate(true);
- case _STATE_EXTRA_ERROR: AsyncError prefetch = DEVC$RT.cast(_futureOrPrefetch, dynamic, AsyncError, "CastGeneral", """line 1011, column 33 of dart:async/stream_impl.dart: """, _futureOrPrefetch is AsyncError, true);
+ case _STATE_EXTRA_ERROR: AsyncError prefetch = DEVC$RT.cast(_futureOrPrefetch, dynamic, AsyncError, "DynamicCast", """line 1011, column 33 of dart:async/stream_impl.dart: """, _futureOrPrefetch is AsyncError, true);
  _clear();
  return new _Future<bool>.immediateError(prefetch.error, prefetch.stackTrace);
  case _STATE_EXTRA_DONE: _clear();
  return new _Future<bool>.immediate(false);
 }
 }
 }
  void _clear() {
 _subscription = null;
  _futureOrPrefetch = null;
  _current = null;
  _state = _STATE_DONE;
 }
  Future cancel() {
 StreamSubscription subscription = _subscription;
  if (_state == _STATE_MOVING) {
 _Future<bool> hasNext = DEVC$RT.cast(_futureOrPrefetch, dynamic, DEVC$RT.type((_Future<bool> _) {
 }
-), "CastGeneral", """line 1033, column 31 of dart:async/stream_impl.dart: """, _futureOrPrefetch is _Future<bool>, false);
+), "CompositeCast", """line 1033, column 31 of dart:async/stream_impl.dart: """, _futureOrPrefetch is _Future<bool>, false);
  _clear();
  hasNext._complete(false);
 }
  else {
 _clear();
 }
  return subscription.cancel();
 }
  void _onData(T data) {
 if (_state == _STATE_MOVING) {
 _current = data;
  _Future<bool> hasNext = DEVC$RT.cast(_futureOrPrefetch, dynamic, DEVC$RT.type((_Future<bool> _) {
 }
-), "CastGeneral", """line 1045, column 31 of dart:async/stream_impl.dart: """, _futureOrPrefetch is _Future<bool>, false);
+), "CompositeCast", """line 1045, column 31 of dart:async/stream_impl.dart: """, _futureOrPrefetch is _Future<bool>, false);
  _futureOrPrefetch = null;
  _state = _STATE_FOUND;
  hasNext._complete(true);
  return;}
  _subscription.pause();
  assert (_futureOrPrefetch == null); _futureOrPrefetch = data;
  _state = _STATE_EXTRA_DATA;
 }
  void _onError(Object error, [StackTrace stackTrace]) {
 if (_state == _STATE_MOVING) {
 _Future<bool> hasNext = DEVC$RT.cast(_futureOrPrefetch, dynamic, DEVC$RT.type((_Future<bool> _) {
 }
-), "CastGeneral", """line 1059, column 31 of dart:async/stream_impl.dart: """, _futureOrPrefetch is _Future<bool>, false);
+), "CompositeCast", """line 1059, column 31 of dart:async/stream_impl.dart: """, _futureOrPrefetch is _Future<bool>, false);
  _clear();
  hasNext._completeError(error, stackTrace);
  return;}
  _subscription.pause();
  assert (_futureOrPrefetch == null); _futureOrPrefetch = new AsyncError(error, stackTrace);
  _state = _STATE_EXTRA_ERROR;
 }
  void _onDone() {
 if (_state == _STATE_MOVING) {
 _Future<bool> hasNext = DEVC$RT.cast(_futureOrPrefetch, dynamic, DEVC$RT.type((_Future<bool> _) {
 }
-), "CastGeneral", """line 1073, column 31 of dart:async/stream_impl.dart: """, _futureOrPrefetch is _Future<bool>, false);
+), "CompositeCast", """line 1073, column 31 of dart:async/stream_impl.dart: """, _futureOrPrefetch is _Future<bool>, false);
  _clear();
  hasNext._complete(false);
  return;}
  _subscription.pause();
  _futureOrPrefetch = null;
  _state = _STATE_EXTRA_DONE;
 }
 }
  typedef void __t87<T>(T __u88);
  typedef void __t89(dynamic __u90);
  typedef dynamic __t92(dynamic __u93);
  typedef dynamic __t95(dynamic __u96, dynamic __u97);
  typedef void __t99(StreamSubscription<dynamic> __u100);