Add a platform plugin infrastructure.

lib/src/runner/plugin/remote_platform_helpers.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.
+
+import 'package:stream_channel/stream_channel.dart';
+
+import '../../utils.dart';
+import '../remote_listener.dart';
+
+/// Returns a channel that will emit a serialized representation of the tests
+/// defined in [getMain].
+///
+/// This channel is used to control the tests. Platform plugins should forward
+/// it to the return value of [PlatformPlugin.loadChannel]. It's guaranteed to
+/// communicate using only JSON-serializable values.
+///
+/// Any errors thrown within [getMain], synchronously or not, will be forwarded
+/// to the load test for this suite. Prints will similarly be forwarded to that
+/// test's print stream.
+///
+/// If [hidePrints] is `true` (the default), calls to `print()` within this
+/// suite will not be forwarded to the parent zone's print handler. However, the
+/// caller may want them to be forwarded in (for example) a browser context
+/// where they'll be visible in the development console.
+StreamChannel serializeSuite(AsyncFunction getMain(),
+        {bool hidePrints: true}) =>
+    RemoteListener.start(getMain, hidePrints: hidePrints);