Isolate.spawn{Uri} only reports errors asynchronously.

tests/isolate/static_function_test.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // Test starting isolate with static functions (and toplevel ones, for sanity).
 
 library static_function_test;
 import 'dart:isolate';
 import 'dart:async';
 import 'static_function_lib.dart' as lib;
@@ skipping 54 matching lines @@
       Isolate.spawn(function, r.sendPort);
       r.listen(expectAsync1((v) {
         expect(v, response);
         r.close();
       }));
   });
 }
 
 void throwsTest(name, function) {
   test("throws on $name", () {
-    expect(() { Isolate.spawn(function, null); }, throws);
+    Isolate.spawn(function, null).catchError(expectAsync1((e) {
+      /* do nothing */
+    }));
   });
 }
 
 void main([args, port]) {
   if (testRemote(main, port)) return;
   // Sanity check.
   spawnTest("function", function, "TOP");
   spawnTest("_function", _function, "_TOP");
   spawnTest("lib.function", lib.function, "LIBTOP");
   spawnTest("lib._function", lib.privateFunction, "_LIBTOP");
@@ skipping 13 matching lines @@
   // Negative tests
   throwsTest("static closure", staticClosure);
   throwsTest("dynamic closure", dynamicClosure);
   throwsTest("named dynamic closure", namedDynamicClosure);
   throwsTest("instance closure", new C().instanceClosure);
   throwsTest("initializer closure", new C().constructorInitializerClosure);
   throwsTest("constructor closure", new C().constructorBodyClosure);
   throwsTest("named constructor closure", new C().namedConstructorBodyClosure);
   throwsTest("instance method", new C().instanceMethod);
 }