Move tar archive parsing to C++

runtime/lib/vmservice_patch.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.
 
+patch class Asset {
+  /// Call to request assets from the embedder.
+  /* patch */ static HashMap<String, Asset> request() {
+    HashMap<String, Asset> assets = new HashMap<String, Asset>();
+    Uint8List tarBytes = _requestAssets();
+    if (tarBytes == null) {
+      return assets;
+    }
+    List assetList = _decodeAssets(tarBytes);
+    for (int i = 0; i < assetList.length; i += 2) {
+      var a = new Asset(assetList[i], assetList[i + 1]);
+      assets[a.name] = a;
+    }
+    return assets;
+  }
+}
+
+List _decodeAssets(Uint8List data) native "VMService_DecodeAssets";
+
 patch bool sendIsolateServiceMessage(SendPort sp, List m)
     native "VMService_SendIsolateServiceMessage";
 patch void sendRootServiceMessage(List m)
     native "VMService_SendRootServiceMessage";
 patch void _onStart() native "VMService_OnStart";
 patch void _onExit() native "VMService_OnExit";
 patch bool _vmListenStream(String streamId) native "VMService_ListenStream";
 patch void _vmCancelStream(String streamId) native "VMService_CancelStream";
-patch Uint8List _requestAssets() native "VMService_RequestAssets";
+patch Uint8List _requestAssets() native "VMService_RequestAssets";