Add support for a global configuration file.

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 74 matching lines @@
     })).create();
 
     d.file("test.dart", """
       import 'package:test/test.dart';
 
       void main() {
         test("failure", () => throw "oh no");
       }
     """).create();
 
-    var test = runTest(["test.dart"], reporter: "compact");
+    var test = runTest(["test.dart"]);
     test.stdout.expect(consumeThrough(contains("dart:isolate-patch")));
     test.shouldExit(1);
   });
 
   test("doesn't dartify stack traces for JS-compiled tests with js_trace: true",
       () {
     d.file("dart_test.yaml", JSON.encode({
       "js_trace": true
     })).create();
 
@@ skipping 429 matching lines @@
           test("failure", () => throw "oh no");
         }
       """)
     ]).create();
 
     var test = runTest([]);
     test.stdout.expect(consumeThrough(contains('All tests passed!')));
     test.shouldExit(0);
   });
 }