Fix ddc async test code

pkg/dev_compiler/tool/run.js

Index: pkg/dev_compiler/tool/run.js
diff --git a/pkg/dev_compiler/tool/run.js b/pkg/dev_compiler/tool/run.js
index a7de6ca85cbfd703943baf0489f90e3a4371d759..cca3aeb94bc9c0360113220e2a016c5bdd61126f 100644
--- a/pkg/dev_compiler/tool/run.js
+++ b/pkg/dev_compiler/tool/run.js
@@ -54,20 +54,21 @@ function finish(e) {
 }
 
 var async_helper = requirejs('async_helper').async_helper;
+sdk._isolate_helper.startRootIsolate(() => {}, []);
 async_helper.asyncTestInitialize(finish);
 
 var module = requirejs(test);
 var lib = test.split('/').slice(-1)[0];
 try {
-  var result = sdk._isolate_helper.startRootIsolate(module[lib].main, []);
+  var result = module[lib].main();
   // async_helper tests call finish directly - call here for all other
   // tests.
   if (!async_helper.asyncTestStarted) {
-    if (!result || !(result instanceof dart_sdk.async.Future)) {
+    if (!result || !(sdk.async.Future.is(result))) {
       finish();
     } else {
       // Wait iff result is a future
-      result.then(dart_sdk.dart.dynamic)(() => finish());
+      result.then(sdk.dart.dynamic)(() => finish(), { onError: (e) => finish(e) });
     }
   }
 } catch (e) {