When we have excess callbacks, throw instead of calling error() so that we

pkg/unittest/test/unittest_test.dart

Index: pkg/unittest/test/unittest_test.dart
===================================================================
--- pkg/unittest/test/unittest_test.dart	(revision 19168)
+++ pkg/unittest/test/unittest_test.dart	(working copy)
@@ -296,7 +296,6 @@
             guardAsync(() {
               excesscallback();
               excesscallback();
-              excesscallback();
               callback();
             });
           });
@@ -321,6 +320,7 @@
             guardAsync(() {
               excesscallback();
               excesscallback();
+              excesscallback();
               callback();
             });
           });
@@ -378,7 +378,7 @@
     buildStatusString(1, 0, 0, 'a ${tests[6]}', count: 0,
         setup: 'setup', teardown: 'teardown'),
     buildStatusString(1, 0, 0, tests[7], count: 1),
-    buildStatusString(0, 0, 1, tests[8], count: 1,
+    buildStatusString(0, 1, 0, tests[8], count: 1,
         message: 'Callback called more times than expected (2 > 1).'),
     buildStatusString(1, 0, 0, tests[9], count: 10),
     buildStatusString(0, 1, 0, tests[10], message: 'Caught error!'),
@@ -396,19 +396,19 @@
         'bad setup/bad teardown foo4:bad setup/bad teardown '
         'foo4: Test teardown failed: Failed to complete tearDown:'
         'post groups'),
-    buildStatusString(2, 2, 2,
+    buildStatusString(2, 3, 1,
         'successful::'
-        'error1:Callback called more times than expected (3 > 1).:'
+        'error1:Caught Callback called more times than expected (3 > 1).:'
         'fail1:Expected: <false> but: was <true>.:'
         'error2:Callback called more times than expected (2 > 1).:'
         'fail2:failure:'
         'foo5'),
-    buildStatusString(2, 2, 2,
+    buildStatusString(2, 3, 1,
         'successful::'
         'fail1:Expected: <false> but: was <true>.:'
-        'error1:Callback called more times than expected (3 > 1).:'
+        'error1:Callback called more times than expected (2 > 1).:'
         'fail2:failure:'
-        'error2:Callback called more times than expected (2 > 1).:'
+        'error2:Caught Callback called more times than expected (3 > 1).:'
         'foo6'),
   ];