Split out unittest tests whose behavior differs in minified mode.

pkg/unittest/test/test_utils.dart

Index: pkg/unittest/test/test_utils.dart
diff --git a/pkg/unittest/test/test_utils.dart b/pkg/unittest/test/test_utils.dart
index d783665df19e784eb2f760bb88a243d1bdff859b..f0b276d060b8ba6299f9803d60a01ec6911cf650 100644
--- a/pkg/unittest/test/test_utils.dart
+++ b/pkg/unittest/test/test_utils.dart
@@ -2,7 +2,11 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-part of unittestTests;
+library test_utils;
+
+import 'package:unittest/unittest.dart';
+
+import 'dart:async';
 
 int errorCount;
 String errorString;
@@ -58,3 +62,20 @@ void shouldPass(value, Matcher matcher, {bool isAsync: false}) {
     afterTest();
   }
 }
+
+doesNotThrow() {}
+doesThrow() { throw 'X'; }
+
+class PrefixMatcher extends BaseMatcher {
+  final String _prefix;
+  const PrefixMatcher(this._prefix);
+  bool matches(item, MatchState matchState) {
+    return item is String &&
+        (collapseWhitespace(item)).startsWith(collapseWhitespace(_prefix));
+  }
+
+  Description describe(Description description) =>
+    description.add('a string starting with ').
+        addDescriptionOf(collapseWhitespace(_prefix)).
+        add(' ignoring whitespace');
+}