Get rid of isolate buffering.

Since we don't load isolates from code being generated by the main
isolate, there's no need to work around dart-lang/sdk#12617. This
dramatically decreases load times for VM tests.

Author: nex3

lib/src/util/dart.dart

@@ -31,55 +31,21 @@ Future<IsolateWrapper> runInIsolate(String code, message, {packageRoot}) async {
   var dir = createTempDir();
   var dartPath = p.join(dir, 'runInIsolate.dart');
   new File(dartPath).writeAsStringSync(code);
-  var port = new ReceivePort();
 
-  try {
-    var isolate = await Isolate.spawn(_isolateBuffer, {
-      'replyTo': port.sendPort,
-      'uri': p.toUri(dartPath).toString(),
-      'packageRoot': packageRoot == null ? null : packageRoot.toString(),
-      'message': message
-    });
-
-    var response = await port.first;
-    if (response['type'] != 'error') {
-      return new IsolateWrapper(isolate,
-          () => new Directory(dir).deleteSync(recursive: true));
-    }
+  if (packageRoot is String) packageRoot = Uri.parse(packageRoot);
 
-    isolate.kill();
-    var asyncError = RemoteException.deserialize(response['error']);
-    await new Future.error(asyncError.error, asyncError.stackTrace);
-    throw 'unreachable';
+  try {
+    var isolate = await Isolate.spawnUri(
+        p.toUri(dartPath), [], message,
+        packageRoot: packageRoot);
+    return new IsolateWrapper(isolate,
+        () => new Directory(dir).deleteSync(recursive: true));
   } catch (error) {
     new Directory(dir).deleteSync(recursive: true);
     rethrow;
   }
 }
 
-// TODO(nweiz): remove this when issue 12617 is fixed.
-/// A function used as a buffer between the host isolate and [spawnUri].
-///
-/// [spawnUri] synchronously loads the file and its imports, which can deadlock
-/// the host isolate if there's an HTTP import pointing at a server in the host.
-/// Adding an additional isolate in the middle works around this.
-Future _isolateBuffer(message) async {
-  var replyTo = message['replyTo'];
-  var packageRoot = message['packageRoot'];
-  if (packageRoot != null) packageRoot = Uri.parse(packageRoot);
-
-  try {
-    await Isolate.spawnUri(Uri.parse(message['uri']), [], message['message'],
-        packageRoot: packageRoot);
-    replyTo.send({'type': 'success'});
-  } catch (error, stackTrace) {
-    replyTo.send({
-      'type': 'error',
-      'error': RemoteException.serialize(error, stackTrace)
-    });
-  }
-}
-
 // TODO(nweiz): Move this into the analyzer once it starts using SourceSpan
 // (issue 22977).
 /// Takes a span whose source is the value of a string that has been parsed from

lib/src/util/isolate_wrapper.dart

@@ -42,6 +42,7 @@ class IsolateWrapper {
   String toString() => _inner.toString();
 
   void kill() {
+    _inner.kill();
     _onExit();
   }
 }