Add a JSON reporter.

test/runner/compact_reporter_test.dart

 // Copyright (c) 2015, 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 'package:scheduled_test/descriptor.dart' as d;
 import 'package:scheduled_test/scheduled_stream.dart';
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../io.dart';
 
 void main() {
   useSandbox();
 
   test("reports when no tests are run", () {
     d.file("test.dart", "void main() {}").create();
 
-    var test = runTest(["test.dart"], compact: true);
+    var test = runTest(["test.dart"], reporter: "compact");
     test.stdout.expect(consumeThrough(contains("No tests ran.")));
     test.shouldExit(0);
   });
 
   test("runs several successful tests and reports when each completes", () {
     _expectReport("""
         test('success 1', () {});
         test('success 2', () {});
         test('success 3', () {});""",
         """
@@ skipping 39 matching lines @@
     d.file("test.dart", """
 import 'dart:async';
 
 import 'package:test/test.dart';
 
 void main() {
   test("failure", () => throw "oh no");
 }
 """).create();
 
-    var test = runTest(["--verbose-trace", "test.dart"], compact: true);
+    var test = runTest(["--verbose-trace", "test.dart"], reporter: "compact");
     test.stdout.expect(consumeThrough(contains("dart:isolate-patch")));
     test.shouldExit(1);
   });
 
   test("runs failing tests along with successful tests", () {
     _expectReport("""
         test('failure 1', () => throw new TestFailure('oh no'));
         test('success 1', () {});
         test('failure 2', () => throw new TestFailure('oh no'));
         test('success 2', () {});""",
@@ skipping 309 matching lines @@
 
 import 'package:test/test.dart';
 
 void main() {
 $tests
 }
 """;
 
   d.file("test.dart", dart).create();
 
-  var test = runTest(["test.dart"], compact: true);
+  var test = runTest(["test.dart"], reporter: "compact");
   test.shouldExit();
 
   schedule(() async {
     var stdoutLines = await test.stdoutStream().toList();
 
     // Skip the first CR, remove excess trailing whitespace, and trim off
     // timestamps.
     var lastLine;
     var actual = stdoutLines.skip(1).map((line) {
       if (line.startsWith("  ") || line.isEmpty) return line.trimRight();
@@ skipping 11 matching lines @@
     // Un-indent the expected string.
     var indentation = expected.indexOf(new RegExp("[^ ]"));
     expected = expected.split("\n").map((line) {
       if (line.isEmpty) return line;
       return line.substring(indentation);
     }).join("\n");
 
     expect(actual, equals(expected));
   });
 }