Move tar archive parsing to C++

sdk/lib/vmservice/asset.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.
 
 part of dart._vmservice;
 
 class Asset {
   final String name;
   final Uint8List data;
 
@@ skipping 20 matching lines @@
       case 'jpeg':
         return 'image/jpeg';
       case 'svg':
         return 'image/svg+xml';
       default:
         return 'text/plain';
     }
   }
 
   /// Call to request assets from the embedder.
-  static Map<String, Asset> request() {
-    Map<String, Asset> assets = new Map<String, Asset>();
+  static HashMap<String, Asset> request() {
+    HashMap<String, Asset> assets = new HashMap<String, Asset>();
     Uint8List tarBytes = _requestAssets();
     if (tarBytes == null) {
       return assets;
     }
     _TarArchive archive = new _TarArchive(tarBytes);
     while (archive.hasNext()) {
       Asset asset = archive.next();
       if (asset == null) {
         // Skip over special files.
         continue;
@@ skipping 143 matching lines @@
     int type = _readType(_bs);
     _bs.seekToNextBlock(tarHeaderSize);
     if (type != tarHeaderFileType) {
       _skipContents(_bs, size);
       return null;
     }
     Uint8List bytes = _readContents(_bs, size);
     return new Asset(filename, bytes);
   }
 }