Merge the Sky Engine changes from the SkyDart branch

This CL flips the switch to make Sky use Dart.

TBR=eseidel@chromium.org
BUG=454613

Review URL: https://codereview.chromium.org/922893002

examples/dart-library.sky

+<div>
+<script>
+
+getPlace() {
+  return "world";
+}
+
+</script>
+</div>

examples/dart-mojo.sky

+#!mojo mojo:sky_viewer
+<sky>
+<import src="dart-library.sky" as="library" />
+<script>
+import 'dart:async';
+import '/mojo/public/dart/application.dart';
+import 'dart:mojo_bindings';
+import 'dart:mojo_core';
+import 'dart:typed_data';
+import 'dart:sky.internals' as internals;
+
+import 'package:mojo/services/network/public/interfaces/network_service.mojom.dart';
+import 'package:mojo/services/network/public/interfaces/url_loader.mojom.dart';
+import 'package:mojo/public/interfaces/application/shell.mojom.dart' as shell_mojom;
+
+class WGet extends Application {
+  NetworkServiceProxy _networkService;
+  UrlLoaderProxy _urlLoaderProxy;
+
+  WGet.fromHandle(MojoHandle handle) : super.fromHandle(handle);
+  WGet(MojoMessagePipeEndpoint endpoint) : super(endpoint);
+
+  void initialize(List<String> args) {
+    run(args);
+  }
+
+  run(List<String> args) async {
+    if (args == null || args.length != 2) {
+      throw "Expected URL argument";
+    }
+
+    ByteData bodyData = await _getUrl(args[1]);
+    print("read ${bodyData.lengthInBytes} bytes");
+
+    _closeProxies();
+    close();
+  }
+
+  Future<ByteData> _getUrl(String url) async {
+    _initProxiesIfNeeded();
+
+    var urlRequest = new UrlRequest()
+        ..url = url
+        ..autoFollowRedirects = true;
+
+    var urlResponse = await _urlLoaderProxy.start(urlRequest);
+    print("url => ${urlResponse.response.url}");
+    print("status_line => ${urlResponse.response.statusLine}");
+    print("mime_type => ${urlResponse.response.mimeType}");
+
+    return DataPipeDrainer.drainHandle(urlResponse.response.body);
+  }
+
+  void _initProxiesIfNeeded() {
+    if (_networkService == null) {
+      _networkService = new NetworkServiceProxy.unbound();
+      connectToService("mojo:network_service", _networkService);
+    }
+    if (_urlLoaderProxy == null) {
+      _urlLoaderProxy = new UrlLoaderProxy.unbound();
+      _networkService.createUrlLoader(_urlLoaderProxy);
+    }
+  }
+
+  void _closeProxies() {
+    _urlLoaderProxy.close();
+    _networkService.close();
+    _urlLoaderProxy = null;
+    _networkService = null;
+  }
+}
+
+main() {
+  var messagePipe = new MojoMessagePipe();
+  var wget = new WGet(messagePipe.endpoints[1]);
+  wget.listen();
+  var shellProxy = new shell_mojom.ShellProxy.fromHandle(new MojoHandle(internals.passShellProxyHandle()));
+  wget.initializeFromShellProxy(shellProxy, ["mojo:wget", "http://www.google.com"]);
+}
+
+</script>
+</sky>

examples/dart.sky

+#!mojo mojo:sky_viewer
+<sky>
+<import src="dart-library.sky" as="library" />
+<script>
+import "dart:sky" as sky;
+
+main() {
+  var text = new sky.Text("Hello");
+  print(text.data);
+  // print(text.firstChild);
+}
+</script>
+</sky>
+w

examples/spinning-square.sky

 #!mojo mojo:sky_viewer
 <sky>
-<import src="fps-counter.sky" />
 <style>
 square {
   margin: 50px;
@@ -10,20 +9,23 @@ square {
 }
 </style>
 <square />
-<fps-counter showHistory="true" />
 <script>
-var square = document.querySelector('square');
-var timeBase = 0;
+import "dart:sky";
 
-function animate(time) {
-  if (!timeBase)
-    timeBase = time;
-  var delta = time - timeBase;
-  var rotation = Math.floor(delta / 10);
-  square.style.transform = 'rotate(' + rotation + 'deg)';
-  requestAnimationFrame(animate);
-}
+void main() {
+  Element square = document.querySelector('square');
+  double timeBase = null;
+
+  void animate(double time) {
+    if (timeBase == null)
+      timeBase = time;
+    double delta = time - timeBase;
+    int rotation = (delta / 10).floor();
+    square.style.setProperty("transform", 'rotate(${rotation}deg)');
+    window.requestAnimationFrame(animate);
+  }
 
-requestAnimationFrame(animate);
+  window.requestAnimationFrame(animate);
+}
 </script>
 </sky>