Change isFalse to test against false instead of against true. (Issue 6611).

pkg/unittest/test/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 unittestTests;
 import '../../../pkg/unittest/lib/unittest.dart';
 part 'test_utils.dart';
 
 doesNotThrow() {}
 doesThrow() { throw 'X'; }
@@ skipping 30 matching lines @@
 
   group('Core matchers', () {
 
     test('isTrue', () {
       shouldPass(true, isTrue);
       shouldFail(false, isTrue, "Expected: true but: was <false>.");
     });
 
     test('isFalse', () {
       shouldPass(false, isFalse);
+      shouldFail(10, isFalse, "Expected: false but: was <10>.");
       shouldFail(true, isFalse, "Expected: false but: was <true>.");
     });
 
     test('isNull', () {
       shouldPass(null, isNull);
       shouldFail(false, isNull, "Expected: null but: was <false>.");
     });
 
     test('isNotNull', () {
       shouldPass(false, isNotNull);
@@ skipping 475 matching lines @@
       var w = new Widget();
       w.price = 10;
       shouldPass(w, new HasPrice(greaterThan(0)));
       shouldFail(w, new HasPrice(greaterThan(10)),
           'Expected: Widget with a price that is a value greater than <10> '
           'but: price was <10>.');
     });
   });
 }