Use metadata annotation @patch for patch classes

runtime/lib/vmservice_patch.dart

Index: runtime/lib/vmservice_patch.dart
diff --git a/runtime/lib/vmservice_patch.dart b/runtime/lib/vmservice_patch.dart
index 498bda2d71dcbdd69f3c3e0265d0d0b7527c9c32..e0a2e024d1f691fec9f17540ec820bd3e613b61b 100644
--- a/runtime/lib/vmservice_patch.dart
+++ b/runtime/lib/vmservice_patch.dart
@@ -2,9 +2,9 @@
 // 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.
 
-patch class Asset {
+@patch class Asset {
   /// Call to request assets from the embedder.
-  /* patch */ static HashMap<String, Asset> request() {
+  /* @patch */ static HashMap<String, Asset> request() {
     HashMap<String, Asset> assets = new HashMap<String, Asset>();
     Uint8List tarBytes = _requestAssets();
     if (tarBytes == null) {
@@ -21,18 +21,18 @@ patch class Asset {
 
 List _decodeAssets(Uint8List data) native "VMService_DecodeAssets";
 
-patch bool sendIsolateServiceMessage(SendPort sp, List m)
+@patch bool sendIsolateServiceMessage(SendPort sp, List m)
     native "VMService_SendIsolateServiceMessage";
-patch void sendRootServiceMessage(List m)
+@patch void sendRootServiceMessage(List m)
     native "VMService_SendRootServiceMessage";
-patch void sendObjectRootServiceMessage(List m)
+@patch void sendObjectRootServiceMessage(List m)
     native "VMService_SendObjectRootServiceMessage";
-patch void _onStart() native "VMService_OnStart";
-patch void _onExit() native "VMService_OnExit";
-patch void onServerAddressChange(String address)
+@patch void _onStart() native "VMService_OnStart";
+@patch void _onExit() native "VMService_OnExit";
+@patch void onServerAddressChange(String address)
     native "VMService_OnServerAddressChange";
-patch bool _vmListenStream(String streamId) native "VMService_ListenStream";
-patch void _vmCancelStream(String streamId) native "VMService_CancelStream";
-patch Uint8List _requestAssets() native "VMService_RequestAssets";
-patch void _spawnUriNotify(obj, String token)
+@patch bool _vmListenStream(String streamId) native "VMService_ListenStream";
+@patch void _vmCancelStream(String streamId) native "VMService_CancelStream";
+@patch Uint8List _requestAssets() native "VMService_RequestAssets";
+@patch void _spawnUriNotify(obj, String token)
     native "VMService_spawnUriNotify";