fixes #52, fields shadowing getters/setters or other fields

lib/runtime/dart/async.js

 var async;
 (function(exports) {
   'use strict';
   // Function _invokeErrorHandler: (Function, Object, StackTrace) → dynamic
   function _invokeErrorHandler(errorHandler, error, stackTrace) {
     if (dart.is(errorHandler, ZoneBinaryCallback)) {
       return dart.dcall(errorHandler, error, stackTrace);
     } else {
       return dart.dcall(errorHandler, error);
     }
   }
   // Function _registerErrorHandler: (Function, Zone) → Function
   function _registerErrorHandler(errorHandler, zone) {
     if (dart.is(errorHandler, ZoneBinaryCallback)) {
       return zone.registerBinaryCallback(errorHandler);
     } else {
       return zone.registerUnaryCallback(dart.as(errorHandler, dart.functionType(dart.dynamic, [dart.dynamic])));
     }
   }
   let _getBestStackTrace = Symbol('_getBestStackTrace');
   class AsyncError extends core.Object {
     AsyncError(error, stackTrace) {
-      this.error = error;
-      this.stackTrace = stackTrace;
+      dart.initField(AsyncError, this, 'error', error);
+      dart.initField(AsyncError, this, 'stackTrace', stackTrace);
     }
     toString() {
       return this.error.toString();
     }
   }
   AsyncError[dart.implements] = () => [core.Error];
   class _UncaughtAsyncError extends AsyncError {
     _UncaughtAsyncError(error, stackTrace) {
       super.AsyncError(error, _UncaughtAsyncError[_getBestStackTrace](error, stackTrace));
     }
@@ skipping 808 matching lines @@
   let _STATE_FIRING = Symbol('_STATE_FIRING');
   let _setRemoveAfterFiring = Symbol('_setRemoveAfterFiring');
   let _STATE_REMOVE_AFTER_FIRING = Symbol('_STATE_REMOVE_AFTER_FIRING');
   let _removeAfterFiring = Symbol('_removeAfterFiring');
   let _onPause = Symbol('_onPause');
   let _onResume = Symbol('_onResume');
   let _onCancel = Symbol('_onCancel');
   let _recordCancel = Symbol('_recordCancel');
   let _recordPause = Symbol('_recordPause');
   let _recordResume = Symbol('_recordResume');
+  let _STATE_CANCEL_ON_ERROR = Symbol('_STATE_CANCEL_ON_ERROR');
   let _zone = Symbol('_zone');
   let _state = Symbol('_state');
-  let _STATE_CANCEL_ON_ERROR = Symbol('_STATE_CANCEL_ON_ERROR');
   let _onData = Symbol('_onData');
   let _onError = Symbol('_onError');
   let _onDone = Symbol('_onDone');
   let _cancelFuture = Symbol('_cancelFuture');
   let _pending = Symbol('_pending');
   let _setPendingEvents = Symbol('_setPendingEvents');
   let _STATE_HAS_PENDING = Symbol('_STATE_HAS_PENDING');
   let _extractPending = Symbol('_extractPending');
   let _isCanceled = Symbol('_isCanceled');
   let _isPaused = Symbol('_isPaused');
@@ skipping 781 matching lines @@
         return new _Future();
       }
     }
     _DoneSubscription[dart.implements] = () => [StreamSubscription$(T)];
     return _DoneSubscription;
   });
   let _DoneSubscription = _DoneSubscription$();
   class DeferredLibrary extends core.Object {
     DeferredLibrary(libraryName, opts) {
       let uri = opts && 'uri' in opts ? opts.uri : null;
-      this.libraryName = libraryName;
-      this.uri = uri;
+      dart.initField(DeferredLibrary, this, 'libraryName', libraryName);
+      dart.initField(DeferredLibrary, this, 'uri', uri);
     }
     load() {
       throw 'DeferredLibrary not supported. ' + 'please use the `import "lib.dart" deferred as lib` syntax.';
     }
   }
   let _s = Symbol('_s');
   class DeferredLoadException extends core.Object {
     DeferredLoadException(s) {
-      this[_s] = s;
+      dart.initField(DeferredLoadException, this, _s, s);
     }
     toString() {
       return `DeferredLoadException: '${this[_s]}'`;
     }
   }
   DeferredLoadException[dart.implements] = () => [core.Exception];
   let _completeWithValue = Symbol('_completeWithValue');
   let Future$ = dart.generic(function(T) {
     class Future extends core.Object {
       Future(computation) {
@@ skipping 157 matching lines @@
         return new Future.value(null);
       }
     });
     return Future;
   });
   let Future = Future$();
   class TimeoutException extends core.Object {
     TimeoutException(message, duration) {
       if (duration === void 0)
         duration = null;
-      this.message = message;
-      this.duration = duration;
+      dart.initField(TimeoutException, this, 'message', message);
+      dart.initField(TimeoutException, this, 'duration', duration);
     }
     toString() {
       let result = "TimeoutException";
       if (this.duration != null)
         result = `TimeoutException after ${this.duration}`;
       if (this.message != null)
         result = `${result}: ${this.message}`;
       return result;
     }
   }
@@ skipping 1698 matching lines @@
       asFuture(futureValue) {
         if (futureValue === void 0)
           futureValue = null;
         throw new core.UnsupportedError("Cannot change handlers of asBroadcastStream source subscription.");
       }
     }
     _BroadcastSubscriptionWrapper[dart.implements] = () => [StreamSubscription$(T)];
     return _BroadcastSubscriptionWrapper;
   });
   let _BroadcastSubscriptionWrapper = _BroadcastSubscriptionWrapper$();
+  let _STATE_FOUND = Symbol('_STATE_FOUND');
   let _current = Symbol('_current');
   let _futureOrPrefetch = Symbol('_futureOrPrefetch');
-  let _STATE_FOUND = Symbol('_STATE_FOUND');
   let _STATE_DONE = Symbol('_STATE_DONE');
   let _STATE_MOVING = Symbol('_STATE_MOVING');
   let _STATE_EXTRA_DATA = Symbol('_STATE_EXTRA_DATA');
   let _STATE_EXTRA_ERROR = Symbol('_STATE_EXTRA_ERROR');
   let _clear = Symbol('_clear');
   let _STATE_EXTRA_DONE = Symbol('_STATE_EXTRA_DONE');
   let _StreamIteratorImpl$ = dart.generic(function(T) {
     class _StreamIteratorImpl extends core.Object {
       _StreamIteratorImpl(stream) {
         this[_subscription] = null;
@@ skipping 1618 matching lines @@
   exports.ScheduleMicrotaskHandler = ScheduleMicrotaskHandler;
   exports.CreateTimerHandler = CreateTimerHandler;
   exports.CreatePeriodicTimerHandler = CreatePeriodicTimerHandler;
   exports.PrintHandler = PrintHandler;
   exports.ForkHandler = ForkHandler;
   exports.ZoneSpecification = ZoneSpecification;
   exports.ZoneDelegate = ZoneDelegate;
   exports.Zone = Zone;
   exports.runZoned = runZoned;
 })(async || (async = {}));