Fix the matcher tests in dart2js minified mode.

pkg/matcher/test/core_matchers_test.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // 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.
 
 library matcher.core_matchers_test;
 
 import 'package:matcher/matcher.dart';
 import 'package:unittest/unittest.dart' show test, group;
 
 import 'test_utils.dart';
@@ skipping 37 matching lines @@
   });
 
   test('equals with a set', () {
     var numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
     var set1 = numbers.toSet();
     numbers.shuffle();
     var set2 = numbers.toSet();
 
     shouldPass(set2, equals(set1));
     shouldPass(numbers, equals(set1));
-    shouldFail([1, 2, 3, 4, 5, 6, 7, 8, 9], equals(set1),
-        "Expected: ?:[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]\n"
-        "  Actual: [1, 2, 3, 4, 5, 6, 7, 8, 9]\n"
-        "   Which: does not contain 10");
-    shouldFail([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11], equals(set1),
-        "Expected: ?:[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]\n"
-        "  Actual: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]\n"
-        "   Which: larger than expected");
+    shouldFail([1, 2, 3, 4, 5, 6, 7, 8, 9], equals(set1), matches(
+        r"Expected: .*:\[1, 2, 3, 4, 5, 6, 7, 8, 9, 10\]"
+        r"  Actual: \[1, 2, 3, 4, 5, 6, 7, 8, 9\]"
+        r"   Which: does not contain 10"));
+    shouldFail([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11], equals(set1), matches(
+        r"Expected: .*:\[1, 2, 3, 4, 5, 6, 7, 8, 9, 10\]"
+        r"  Actual: \[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11\]"
+        r"   Which: larger than expected"));
   });
 
   test('anything', () {
     var a = new Map();
     shouldPass(0, anything);
     shouldPass(null, anything);
     shouldPass(a, anything);
     shouldFail(a, isNot(anything), "Expected: not anything Actual: {}");
   });
 
@@ skipping 144 matching lines @@
   });
 }
 
 class _Bicycle {
   static final foo = bar();
 
   static bar() {
     return foo + 1;
   }
 }