Added Sky Mojo embedder singleton, restored network test

sky/tests/resources/event-sender.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import "/sky/framework/shell.dart" as shell;
+import "/sky/framework/embedder.dart";
 import "dart:async";
 import "dart:sky";
 import "dart:sky.internals" as internals;
 import "package:mojo/services/input_events/public/interfaces/input_event_constants.mojom.dart" as constants;
 import "package:mojo/services/input_events/public/interfaces/input_events.mojom.dart" as events;
 import "package:mojo/services/input_events/public/interfaces/input_key_codes.mojom.dart" as codes;
 import "package:sky/services/testing/test_harness.mojom.dart" as harness;
 
 bool _isDone = false;
 int _keyPressesRemaining = 0;
@@ skipping 39 matching lines @@
 
 void handleKeyPress_(Event event) {
   --_keyPressesRemaining;
   _checkComplete();
 }
 
 harness.TestHarnessProxy _init() {
   document.addEventListener('keypress', handleKeyPress_);
 
   var harnessProxy = new harness.TestHarnessProxy.unbound();
-  shell.connectToService("mojo:sky_tester", harnessProxy);
+  embedder.connectToService("mojo:sky_tester", harnessProxy);
   return harnessProxy;
 }
 
 final harness.TestHarnessProxy _harness = _init();
 
 // |0| should be EventFlags_NONE once its a compile-time constant.
 void keyDown(int keyCode, [int eventFlags = 0]) {
   if (!_chars.contains(keyCode)) {
     _harness.dispatchInputEvent(
         new events.Event()
@@ skipping 24 matching lines @@
                      ..unmodifiedText = keyCode));
   }
 }
 
 void done() {
   if (_isDone)
     throw "Already done.";
   _isDone = true;
   _checkComplete();
 }