Fix all strong-mode errors and warnings.

lib/src/runner/load_suite.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.
 
 import 'dart:async';
 
 import 'package:stack_trace/stack_trace.dart';
 
 import '../../test.dart';
 import '../backend/group.dart';
@@ skipping 47 matching lines @@
 
   /// Creates a load suite named [name] on [platform].
   ///
   /// [body] may return either a [RunnerSuite] or a [Future] that completes to a
   /// [RunnerSuite]. Its return value is forwarded through [suite], although if
   /// it throws an error that will be forwarded through the suite's test.
   ///
   /// If the the load test is closed before [body] is complete, it will close
   /// the suite returned by [body] once it completes.
   factory LoadSuite(String name, body(), {String path, TestPlatform platform}) {
-    var completer = new Completer.sync();
+    var completer = new Completer<Pair<RunnerSuite, Zone>>.sync();
     return new LoadSuite._(name, () {
       var invoker = Invoker.current;
       invoker.addOutstandingCallback();
 
       invoke(() async {
         try {
           var suite = await body();
           if (completer.isCompleted) {
             // If the load test has already been closed, close the suite it
             // generated.
@@ skipping 43 matching lines @@
       : super(new Group.root([
         new LocalTest(name,
             new Metadata(timeout: new Timeout(new Duration(minutes: 5))),
             body)
       ]), path: path, platform: platform);
 
   /// A constructor used by [changeSuite].
   LoadSuite._changeSuite(LoadSuite old, this._suiteAndZone)
       : super(old.group, path: old.path, platform: old.platform);
 
+  /// A constructor used by [filter].
+  LoadSuite._filtered(LoadSuite old, Group filtered)
+      : _suiteAndZone = old._suiteAndZone,
+        super(old.group, path: old.path, platform: old.platform);
+
   /// Creates a new [LoadSuite] that's identical to this one, but that
   /// transforms [suite] once it's loaded.
   ///
   /// If [suite] completes to `null`, [change] won't be run. [change] is run
   /// within the load test's zone, so any errors or prints it emits will be
   /// associated with that test.
   LoadSuite changeSuite(RunnerSuite change(RunnerSuite suite)) {
     return new LoadSuite._changeSuite(this, _suiteAndZone.then((pair) {
       if (pair == null) return null;
 
@@ skipping 12 matching lines @@
     liveTest.onPrint.listen(print);
     await liveTest.run();
 
     if (liveTest.errors.isEmpty) return await suite;
 
     var error = liveTest.errors.first;
     await new Future.error(error.error, error.stackTrace);
     throw 'unreachable';
   }
 
+  LoadSuite filter(bool callback(Test test)) {
+    var filtered = this.group.filter(callback);
+    if (filtered == null) filtered = new Group.root([], metadata: metadata);
+    return new LoadSuite._filtered(this, filtered);
+  }
+
   Future close() async {}
 }