fixes #177, FunctionDeclarationStatement and closing over `this`

lib/runtime/dart/isolate.js

 var isolate = dart.defineLibrary(isolate, {});
 var core = dart.import(core);
 var _isolate_helper = dart.lazyImport(_isolate_helper);
 var async = dart.import(async);
 (function(exports, core, _isolate_helper, async) {
   'use strict';
   class Capability extends core.Object {
     Capability() {
       return new _isolate_helper.CapabilityImpl();
     }
@@ skipping 114 matching lines @@
     removeErrorListener(port) {
       let message = new core.List(2);
       message[core.$set](0, "stopErrors");
       message[core.$set](1, port);
       this.controlPort.send(message);
     }
     get errors() {
       let controller = null;
       let port = null;
       // Function handleError: (dynamic) → void
-      function handleError(message) {
+      let handleError = message => {
         let errorDescription = dart.as(dart.dindex(message, 0), core.String);
         let stackDescription = dart.as(dart.dindex(message, 1), core.String);
         let error = new RemoteError(errorDescription, stackDescription);
         controller.addError(error, error.stackTrace);
-      }
+      };
       controller = new async.StreamController.broadcast({
         sync: true,
         onListen: (() => {
           port = new RawReceivePort(handleError);
           this.addErrorListener(port.sendPort);
         }).bind(this),
         onCancel: (() => {
           this.removeErrorListener(port.sendPort);
           port.close();
           port = null;
@@ skipping 63 matching lines @@
   _RemoteStackTrace[dart.implements] = () => [core.StackTrace];
   // Exports:
   exports.Capability = Capability;
   exports.IsolateSpawnException = IsolateSpawnException;
   exports.Isolate = Isolate;
   exports.SendPort = SendPort;
   exports.ReceivePort = ReceivePort;
   exports.RawReceivePort = RawReceivePort;
   exports.RemoteError = RemoteError;
 })(isolate, core, _isolate_helper, async);