Run dart2js tests unmodified in browser.

dart/pkg/unittest/config.dart

Index: dart/pkg/unittest/config.dart
diff --git a/dart/pkg/unittest/config.dart b/dart/pkg/unittest/config.dart
index 34693dde24f6b99fea5b0c1e0c69527979deaec2..5a8b4bcce5c5814b8fd2f5ef45be2087575945bc 100644
--- a/dart/pkg/unittest/config.dart
+++ b/dart/pkg/unittest/config.dart
@@ -37,7 +37,9 @@ class Configuration {
    * tell the vm or browser that tests are still running and the process should
    * wait until they are done.
    */
-  void onStart() {}
+  void onStart() {
+    _postMessage('unittest-suite-wait-for-done');
+  }
 
   /**
    * Called when each test starts. Useful to show intermediate progress on
@@ -121,8 +123,11 @@ class Configuration {
       print('$passed PASSED, $failed FAILED, $errors ERRORS');
     }
 
-    // An exception is used by the test infrastructure to detect failure.
-    if (!success) throw new Exception("Some tests failed.");
+    if (success) {
+      _postMessage('unittest-suite-success');
+    } else {
+      throw new Exception('Some tests failed.');
+    }
   }
 
   String _indent(String str) {
@@ -137,4 +142,10 @@ class Configuration {
   // Currently e.message works in dartium, but not in dartc.
   handleExternalError(e, String message) =>
       _reportTestError('$message\nCaught $e', '');
+
+  _postMessage(String message) {
+    // In dart2js browser tests, the JavaScript-based test controller
+    // intercepts calls to print and listens for "secret" messages.
+    print(message);

[kasperl, 2012/09/10 10:46:30]

Would it make sense to add a prefix to these messages here? Somehow that would
make it easier to grok that the postMessage implementation here does its trick
and encodes the secret messages instead of letting all users of postMessage deal
with it?

   print("POSTMESSAGE: $message");

[ahe, 2012/09/10 10:48:05]

There is already a prefix, "unittest-". I'm not sure there is much value to
adding additional prefixes.

+  }
 }