pkg/unittest: no need to expose the errorHandler helper

pkg/unittest/lib/src/test_case.dart

Index: pkg/unittest/lib/src/test_case.dart
diff --git a/pkg/unittest/lib/src/test_case.dart b/pkg/unittest/lib/src/test_case.dart
index 9bf3656924af7ff64be69746a083891b21c57e85..ad5bd6ad8a4b0644a3a9ebfcbb8ffca38f4e75e6 100644
--- a/pkg/unittest/lib/src/test_case.dart
+++ b/pkg/unittest/lib/src/test_case.dart
@@ -67,7 +67,7 @@ class TestCase {
 
   bool get isComplete => !enabled || result != null;
 
-  errorHandler(stage) => (e) {
+  Function _errorHandler(String stage) => (e) {
     var stack = getAttachedStackTrace(e);
     stack = (stack == null) ? '' : '$stack';
     if (result == null || result == PASS) {
@@ -92,7 +92,7 @@ class TestCase {
     _message = '';
 
     var f = (setUp == null) ? new Future.value() : new Future(setUp);
-    return f.catchError(errorHandler('Setup'))
+    return f.catchError(_errorHandler('Setup'))
         .then((_) {
           // Skip the test if setup failed.
           if (result != null) return new Future.value();
@@ -102,7 +102,7 @@ class TestCase {
           ++_callbackFunctionsOutstanding;
           return testFunction();
         })
-        .catchError(errorHandler('Test'))
+        .catchError(_errorHandler('Test'))
         .then((_) {
           _markCallbackComplete();
           if (result == null) {
@@ -112,12 +112,12 @@ class TestCase {
               if (tearDown != null) {
                 return tearDown();
               }
-            }).catchError(errorHandler('Teardown'));
+            }).catchError(_errorHandler('Teardown'));
           } else if (tearDown != null) {
             return tearDown();
           }
         })
-        .catchError(errorHandler('Teardown'));
+        .catchError(_errorHandler('Teardown'));
   }
 
   // Set the results, notify the config, and return true if this