Inference through conditional expressions

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 871 matching lines @@
     static _getEventData(e) {
       return e.data;
     }
     static _processWorkerMessage(sender, e) {
       let msg = _deserializeMessage(IsolateNatives._getEventData(e));
       switch (dart.dindex(msg, 'command')) {
         case 'start':
         {
           exports._globalState.currentManagerId = dart.as(dart.dindex(msg, 'id'), core.int);
           let functionName = dart.as(dart.dindex(msg, 'functionName'), core.String);
-          let entryPoint = dart.as(functionName == null ? exports._globalState.entry : IsolateNatives._getJSFunctionFromName(functionName), core.Function);
+          let entryPoint = functionName == null ? exports._globalState.entry : dart.as(IsolateNatives._getJSFunctionFromName(functionName), core.Function);
           let args = dart.dindex(msg, 'args');
           let message = _deserializeMessage(dart.dindex(msg, 'msg'));
           let isSpawnUri = dart.dindex(msg, 'isSpawnUri');
           let startPaused = dart.dindex(msg, 'startPaused');
           let replyTo = _deserializeMessage(dart.dindex(msg, 'replyTo'));
           let context = new _IsolateContext();
           exports._globalState.topEventLoop.enqueue(context, () => {
             IsolateNatives._startIsolate(entryPoint, dart.as(args, core.List$(core.String)), message, dart.as(isSpawnUri, core.bool), dart.as(startPaused, core.bool), dart.as(replyTo, isolate.SendPort));
           }, 'worker-start');
           exports._globalState.currentContext = context;
@@ skipping 67 matching lines @@
     }
     static _consoleLog(msg) {
       _js_helper.requiresPreamble();
       self.console.log(msg);
     }
     static _getJSFunctionFromName(functionName) {
       let globalFunctionsContainer = _foreign_helper.JS_EMBEDDED_GLOBAL("", _js_embedded_names.GLOBAL_FUNCTIONS);
       return globalFunctionsContainer[functionName]();
     }
     static _getJSFunctionName(f) {
-      return dart.as(dart.is(f, _js_helper.Closure) ? f.$name : null, core.String);
+      return dart.is(f, _js_helper.Closure) ? dart.as(f.$name, core.String) : null;
     }
     static _allocate(ctor) {
       return new ctor();
     }
     static spawnFunction(topLevelFunction, message, startPaused) {
       IsolateNatives.enableSpawnWorker = true;
       let name = IsolateNatives._getJSFunctionName(topLevelFunction);
       if (name == null) {
         throw new core.UnsupportedError("only top-level functions can be spawned.");
       }
@@ skipping 387 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 = {}));