Reverting 32284 - unittest using zones - investigating breaks in html

pkg/unittest/lib/src/spread_args_helper.dart

Index: pkg/unittest/lib/src/spread_args_helper.dart
diff --git a/pkg/unittest/lib/src/spread_args_helper.dart b/pkg/unittest/lib/src/spread_args_helper.dart
index 41411b93780f4f2d68f4f6941dad6186b668f4f4..08dd45868ee6b3a1da9fbabcaa76c83378ead782 100644
--- a/pkg/unittest/lib/src/spread_args_helper.dart
+++ b/pkg/unittest/lib/src/spread_args_helper.dart
@@ -12,6 +12,7 @@ class _SpreadArgsHelper {
   int actualCalls = 0;
   final TestCase testCase;
   bool complete;
+  static const sentinel = const _Sentinel();
 
   _SpreadArgsHelper(Function callback, int minExpected, int maxExpected,
       Function isDone, String id)
@@ -119,15 +120,4 @@ class _SpreadArgsHelper {
         },
         after, testCase);
   }
-
-  _guardAsync(Function tryBody, Function finallyBody, TestCase testCase) {
-    assert(testCase != null);
-    try {
-      return tryBody();
-    } catch (e, trace) {
-      _registerException(testCase, e, trace);
-    } finally {
-      if (finallyBody != null) finallyBody();
-    }
-  }
 }