Make writes consistent across socket and file synchronous/asynchronus writes in terms of truncation…

sdk/lib/io/file_impl.dart

 // Copyright (c) 2013, 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.io;
 
 // Read the file in blocks of size 64k.
 const int _BLOCK_SIZE = 64 * 1024;
 
 
@@ skipping 765 matching lines @@
     if ((buffer is !List && buffer is !ByteData) ||
         (start != null && start is !int) ||
         (end != null && end is !int)) {
       throw new ArgumentError("Invalid arguments to writeFrom");
     }
 
     if (closed) return _closedException();
 
     _BufferAndStart result;
     try {
-      result = _ensureFastAndSerializableData(buffer, start, end);
+      result = _ensureFastAndSerializableByteData(buffer, start, end);
     } catch (e) {
       return new Future.error(e);
     }
 
     List request = new List(5);
     request[0] = _WRITE_LIST_REQUEST;
     request[1] = _id;
     request[2] = result.buffer;
     request[3] = result.start;
     request[4] = end - (start - result.start);
@@ skipping 12 matching lines @@
     if (buffer is !List ||
         (start != null && start is !int) ||
         (end != null && end is !int)) {
       throw new ArgumentError("Invalid arguments to writeFromSync");
     }
     if (start == null) start = 0;
     if (end == null) end = buffer.length;
     if (end == start) return;
     _checkReadWriteListArguments(buffer.length, start, end);
     _BufferAndStart bufferAndStart =
-        _ensureFastAndSerializableData(buffer, start, end);
+        _ensureFastAndSerializableByteData(buffer, start, end);
     var result = _writeFrom(_id,
                             bufferAndStart.buffer,
                             bufferAndStart.start,
                             end - (start - bufferAndStart.start));
     if (result is OSError) {
       throw new FileException("writeFrom failed", _path, result);
     }
   }
 
   Future<RandomAccessFile> writeString(String string,
@@ skipping 157 matching lines @@
 
   Future _closedException() {
     return new Future.error(new FileException("File closed", _path));
   }
 
   final String _path;
   int _id;
 
   SendPort _fileService;
 }