Use destructuring assignments for named parameters (#180)

lib/runtime/dart/_isolate_helper.js

 dart_library.library('dart/_isolate_helper', null, /* Imports */[
   "dart/_runtime",
   'dart/core',
   'dart/_interceptors',
   'dart/_js_helper',
   'dart/isolate',
   'dart/_foreign_helper',
   'dart/collection',
   'dart/async'
 ], /* Lazy imports */[
@@ skipping 16 matching lines @@
     return deserializer.deserialize(serializer.serialize(message));
   }
   dart.fn(_clone);
   let _serializeSendPorts = Symbol('_serializeSendPorts');
   let _workerId = Symbol('_workerId');
   let _isolateId = Symbol('_isolateId');
   let _receivePortId = Symbol('_receivePortId');
   let _id = Symbol('_id');
   let _receivePort = Symbol('_receivePort');
   class _Serializer extends core.Object {
-    _Serializer(opts) {
-      let serializeSendPorts = opts && 'serializeSendPorts' in opts ? opts.serializeSendPorts : true;
+    _Serializer({serializeSendPorts = true} = {}) {
       this.serializedObjectIds = core.Map$(dart.dynamic, core.int).identity();
       this[_serializeSendPorts] = dart.as(serializeSendPorts, core.bool);
     }
     serialize(x) {
       if (dart.notNull(this.isPrimitive(x)))
         return this.serializePrimitive(x);
       let serializationId = this.serializedObjectIds.get(x);
       if (serializationId != null)
         return this.makeRef(serializationId);
       serializationId = this.serializedObjectIds.length;
@@ skipping 135 matching lines @@
       serializeJSObject: [dart.dynamic, [_interceptors.JSObject]],
       serializeWorkerSendPort: [dart.dynamic, [_WorkerSendPort]],
       serializeJsSendPort: [dart.dynamic, [_NativeJsSendPort]],
       serializeCapability: [dart.dynamic, [CapabilityImpl]],
       serializeClosure: [dart.dynamic, [core.Function]],
       serializeDartObject: [dart.dynamic, [dart.dynamic]]
     })
   });
   let _adjustSendPorts = Symbol('_adjustSendPorts');
   class _Deserializer extends core.Object {
-    _Deserializer(opts) {
-      let adjustSendPorts = opts && 'adjustSendPorts' in opts ? opts.adjustSendPorts : true;
+    _Deserializer({adjustSendPorts = true} = {}) {
       this.deserializedObjects = core.List.new();
       this[_adjustSendPorts] = dart.as(adjustSendPorts, core.bool);
     }
     deserialize(x) {
       if (dart.notNull(this.isPrimitive(x)))
         return this.deserializePrimitive(x);
       if (!dart.is(x, _interceptors.JSArray))
         dart.throw(new core.ArgumentError(`Bad serialized message: ${x}`));
       switch (dart.dload(x, 'first')) {
         case "ref":
@@ skipping 1199 matching lines @@
     weak() {
       this.fromRawReceivePort(new RawReceivePortImpl.weak(null));
     }
     fromRawReceivePort(rawPort) {
       this[_rawPort] = rawPort;
       this[_controller] = null;
       super.Stream();
       this[_controller] = async.StreamController.new({onCancel: dart.bind(this, 'close'), sync: true});
       this[_rawPort].handler = dart.bind(this[_controller], 'add');
     }
-    listen(onData, opts) {
-      let onError = opts && 'onError' in opts ? opts.onError : null;
-      let onDone = opts && 'onDone' in opts ? opts.onDone : null;
-      let cancelOnError = opts && 'cancelOnError' in opts ? opts.cancelOnError : null;
+    listen(onData, {onError = null, onDone = null, cancelOnError = null} = {}) {
       return this[_controller].stream.listen(onData, {onError: onError, onDone: onDone, cancelOnError: cancelOnError});
     }
     close() {
       this[_rawPort].close();
       this[_controller].close();
     }
     get sendPort() {
       return this[_rawPort].sendPort;
     }
   }
@@ skipping 131 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;
 });