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

lib/runtime/dart/_isolate_helper.js

 var _isolate_helper;
 (function(exports) {
   'use strict';
   // Function _serializeMessage: (dynamic) → dynamic
   function _serializeMessage(message) {
     return new _Serializer().serialize(message);
   }
   // Function _deserializeMessage: (dynamic) → dynamic
   function _deserializeMessage(message) {
     return new _Deserializer().deserialize(message);
@@ skipping 1178 matching lines @@
       }
     }
     ['=='](other) {
       return dart.is(other, _WorkerSendPort) && dart.equals(this[_workerId], dart.dload(other, _workerId)) && dart.equals(this[_isolateId], dart.dload(other, _isolateId)) && dart.equals(this[_receivePortId], dart.dload(other, _receivePortId));
     }
     get hashCode() {
       return dart.notNull(this[_workerId]) << 16 ^ dart.notNull(this[_isolateId]) << 8 ^ dart.notNull(this[_receivePortId]);
     }
   }
   _WorkerSendPort[dart.implements] = () => [isolate.SendPort];
+  let _nextFreeId = Symbol('_nextFreeId');
   let _handler = Symbol('_handler');
-  let _nextFreeId = Symbol('_nextFreeId');
   class RawReceivePortImpl extends core.Object {
     RawReceivePortImpl(handler) {
-      this[_handler] = handler;
-      this[_id] = (() => {
+      dart.initField(RawReceivePortImpl, this, _handler, handler);
+      dart.initField(RawReceivePortImpl, this, _id, (() => {
         let x = RawReceivePortImpl[_nextFreeId];
         RawReceivePortImpl[_nextFreeId] = dart.notNull(x) + 1;
         return x;
-      })();
-      this[_isClosed] = false;
+      })());
+      dart.initField(RawReceivePortImpl, this, _isClosed, false);
       exports._globalState.currentContext.register(this[_id], this);
     }
     weak(handler) {
-      this[_handler] = handler;
-      this[_id] = (() => {
+      dart.initField(RawReceivePortImpl, this, _handler, handler);
+      dart.initField(RawReceivePortImpl, this, _id, (() => {
         let x = RawReceivePortImpl[_nextFreeId];
         RawReceivePortImpl[_nextFreeId] = dart.notNull(x) + 1;
         return x;
-      })();
-      this[_isClosed] = false;
+      })());
+      dart.initField(RawReceivePortImpl, this, _isClosed, false);
       exports._globalState.currentContext.registerWeak(this[_id], this);
     }
     [_controlPort]() {
-      this[_handler] = null;
-      this[_id] = 0;
-      this[_isClosed] = false;
+      dart.initField(RawReceivePortImpl, this, _handler, null);
+      dart.initField(RawReceivePortImpl, this, _id, 0);
+      dart.initField(RawReceivePortImpl, this, _isClosed, false);
     }
     set handler(newHandler) {
       this[_handler] = newHandler;
     }
     [_close]() {
       this[_isClosed] = true;
       this[_handler] = null;
     }
     close() {
       if (this[_isClosed])
@@ skipping 46 matching lines @@
     }
   }
   ReceivePortImpl[dart.implements] = () => [isolate.ReceivePort];
   dart.defineNamedConstructor(ReceivePortImpl, 'weak');
   dart.defineNamedConstructor(ReceivePortImpl, 'fromRawReceivePort');
   let _once = Symbol('_once');
   let _inEventLoop = Symbol('_inEventLoop');
   let _handle = Symbol('_handle');
   class TimerImpl extends core.Object {
     TimerImpl(milliseconds, callback) {
-      this[_once] = true;
-      this[_inEventLoop] = false;
-      this[_handle] = null;
+      dart.initField(TimerImpl, this, _once, true);
+      dart.initField(TimerImpl, this, _inEventLoop, false);
+      dart.initField(TimerImpl, this, _handle, null);
       if (milliseconds == 0 && (!dart.notNull(hasTimer()) || dart.notNull(exports._globalState.isWorker))) {
         // Function internalCallback: () → void
         function internalCallback() {
           this[_handle] = null;
           callback();
         }
         this[_handle] = 1;
         exports._globalState.topEventLoop.enqueue(exports._globalState.currentContext, internalCallback, 'timer');
         this[_inEventLoop] = true;
       } else if (hasTimer()) {
         // Function internalCallback: () → void
         function internalCallback() {
           this[_handle] = null;
           leaveJsAsync();
           callback();
         }
         enterJsAsync();
         this[_handle] = self.setTimeout(_js_helper.convertDartClosureToJS(internalCallback, 0), milliseconds);
       } else {
         dart.assert(dart.notNull(milliseconds) > 0);
         throw new core.UnsupportedError("Timer greater than 0.");
       }
     }
     periodic(milliseconds, callback) {
-      this[_once] = false;
-      this[_inEventLoop] = false;
-      this[_handle] = null;
+      dart.initField(TimerImpl, this, _once, false);
+      dart.initField(TimerImpl, this, _inEventLoop, false);
+      dart.initField(TimerImpl, this, _handle, null);
       if (hasTimer()) {
         enterJsAsync();
         this[_handle] = self.setInterval(_js_helper.convertDartClosureToJS((() => {
           callback(this);
         }).bind(this), 0), milliseconds);
       } else {
         throw new core.UnsupportedError("Periodic timer.");
       }
     }
     cancel() {
@@ skipping 24 matching lines @@
   function hasTimer() {
     _js_helper.requiresPreamble();
     return self.setTimeout != null;
   }
   let _internal = Symbol('_internal');
   class CapabilityImpl extends core.Object {
     CapabilityImpl() {
       this[_internal](_js_helper.random64());
     }
     [_internal](id) {
-      this[_id] = id;
+      dart.initField(CapabilityImpl, this, _id, id);
     }
     get hashCode() {
       let hash = this[_id];
       hash = dart.notNull(hash) >> 0 ^ (dart.notNull(hash) / 4294967296).truncate();
       hash = ~dart.notNull(hash) + (dart.notNull(hash) << 15) & 4294967295;
       hash = dart.notNull(hash) ^ dart.notNull(hash) >> 12;
       hash = dart.notNull(hash) * 5 & 4294967295;
       hash = dart.notNull(hash) ^ dart.notNull(hash) >> 4;
       hash = dart.notNull(hash) * 2057 & 4294967295;
       hash = dart.notNull(hash) ^ dart.notNull(hash) >> 16;
@@ skipping 15 matching lines @@
   exports.leaveJsAsync = leaveJsAsync;
   exports.isWorker = isWorker;
   exports.startRootIsolate = startRootIsolate;
   exports.IsolateNatives = IsolateNatives;
   exports.RawReceivePortImpl = RawReceivePortImpl;
   exports.ReceivePortImpl = ReceivePortImpl;
   exports.TimerImpl = TimerImpl;
   exports.hasTimer = hasTimer;
   exports.CapabilityImpl = CapabilityImpl;
 })(_isolate_helper || (_isolate_helper = {}));