pkg/unittest: Run each test in a Zone

pkg/unittest/test/unittest_protect_async_test.dart

Index: pkg/unittest/test/unittest_protect_async_test.dart
diff --git a/pkg/unittest/test/unittest_protect_async_test.dart b/pkg/unittest/test/unittest_protect_async_test.dart
index 34b5db3db548d90681a2b00f993bc582882cb134..12ded3cecd0b03be67db1b7e7ac18ba92969f018 100644
--- a/pkg/unittest/test/unittest_protect_async_test.dart
+++ b/pkg/unittest/test/unittest_protect_async_test.dart
@@ -37,7 +37,7 @@ var testFunction = (_) {
 };
 
 var expected = '1:0:3:4:0:::null:'
-  'protectAsync0:Callback called (1) after test case protectAsync0 has already been marked as pass.:'
-  'protectAsync1:Callback called (1) after test case protectAsync1 has already been marked as pass.:'
-  'protectAsync2:Callback called (1) after test case protectAsync2 has already been marked as pass.:'
+  'protectAsync0:Caught Bad state: error during protectAsync0:'
+  'protectAsync1:Caught Bad state: error during protectAsync1: one arg:'
+  'protectAsync2:Caught Bad state: error during protectAsync2: arg1, arg2:'

[Siggi Cherem (dart-lang), 2014/02/04 02:20:05]

can we combine this with the old message? I think it still is important that we
also mention that the callback is called after the test was done.

[kevmoo, 2014/02/04 02:26:18]

Good idea. I'll look into it.

[kevmoo, 2014/02/04 17:52:26]

I added a TODO around this. We need to do a better way to capture and categorize
the classes of errors. During setUp, tearDown, and run. 'in-line' vs Future vs
async.

https://codereview.chromium.org/130173010

[Siggi Cherem (dart-lang), 2014/02/04 17:59:36]

Is there a way to fix this part here to show the old message instead? I think
the real reason the test is failing here is not that there is an error in
'protectAsync', but the fact that the code is running after the test is done. 

What happens currently if the callback has no errors?

   'throw away 1:';