Add browser tags to all of our 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:convert';
 
 import 'package:path/path.dart' as p;
 import 'package:scheduled_test/descriptor.dart' as d;
@@ skipping 52 matching lines @@
         test("failure", () => throw "oh no");
       }
     """).create();
 
     var test = runTest(["-p", "chrome", "--verbose-trace", "test.dart"]);
     test.stdout.fork().expect(never(endsWith(" main.<fn>")));
     test.stdout.fork().expect(never(contains("package:test")));
     test.stdout.fork().expect(never(contains("dart:async/zone.dart")));
     test.stdout.expect(consumeThrough(contains("-1: Some tests failed.")));
     test.shouldExit(1);
-  });
+  }, tags: 'chrome');
 
   test("uses the specified reporter", () {
     d.file("dart_test.yaml", JSON.encode({
       "reporter": "json"
     })).create();
 
     d.file("test.dart", """
       import 'package:test/test.dart';
 
       void main() {
@@ skipping 119 matching lines @@
         test("success", () {});
       }
     """).create();
 
     var test = runTest(["test.dart"]);
     test.stdout.expect(containsInOrder([
       "[VM] success",
       "[Dartium Content Shell] success"
     ]));
     test.shouldExit(0);
-  });
+  }, tags: "content-shell");
 
   test("command line args take precedence", () {
     d.file("dart_test.yaml", JSON.encode({
       "timeout": "0s"
     })).create();
 
     d.file("test.dart", """
       import 'dart:async';
 
       import 'package:test/test.dart';
@@ skipping 77 matching lines @@
           test("failure", () => throw "oh no");
         }
       """)
     ]).create();
 
     var test = runTest([]);
     test.stdout.expect(consumeThrough(contains('All tests passed!')));
     test.shouldExit(0);
   });
 }