Add an option to run skipped tests.

test/runner/configuration/top_level_test.dart

 // Copyright (c) 2016, 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.
 
 @TestOn("vm")
 
 import 'dart:async';
 import 'dart:convert';
 
 import 'package:path/path.dart' as p;
@@ skipping 61 matching lines @@
       // our input.
       await new Future.delayed(new Duration(seconds: 2));
       expect(nextLineFired, isFalse);
     });
 
     test.writeLine('');
     test.stdout.expect(consumeThrough(contains("+1: All tests passed!")));
     test.shouldExit(0);
   }, tags: 'content-shell');
 
+  test("runs skipped tests with run_skipped: true", () {
+    d.file("dart_test.yaml", JSON.encode({
+      "run_skipped": true
+    })).create();
+
+    d.file("test.dart", """
+      import 'package:test/test.dart';
+
+      void main() {
+        test("skip", () => print("In test!"), skip: true);
+      }
+    """).create();
+
+    var test = runTest(["test.dart"]);
+    test.stdout.expect(consumeThrough(contains("In test!")));
+    test.stdout.expect(consumeThrough(contains("+1: All tests passed!")));
+    test.shouldExit(0);
+  });
+
   test("includes the full stack with verbose_trace: true", () {
     d.file("dart_test.yaml", JSON.encode({
       "verbose_trace": true
     })).create();
 
     d.file("test.dart", """
       import 'package:test/test.dart';
 
       void main() {
         test("failure", () => throw "oh no");
@@ skipping 443 matching lines @@
           test("failure", () => throw "oh no");
         }
       """)
     ]).create();
 
     var test = runTest([]);
     test.stdout.expect(consumeThrough(contains('All tests passed!')));
     test.shouldExit(0);
   });
 }