Fix win32 build break.

vm/snapshot.h

 // Copyright (c) 2011, 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.
 
 #ifndef VM_SNAPSHOT_H_
 #define VM_SNAPSHOT_H_
 
 #include "vm/allocation.h"
 #include "vm/assert.h"
 #include "vm/bitfield.h"
@@ skipping 248 matching lines @@
 
  private:
   uint8_t** const buffer_;
   uint8_t* end_;
   uint8_t* current_;
   intptr_t current_size_;
   ReAlloc alloc_;
 
   // MessageWriter and SnapshotWriter needs access to the private Raw
   // classes.
-  friend class MessageWriter;
-  friend class SnapshotWriter;
+  friend class BaseWriter;
   DISALLOW_COPY_AND_ASSIGN(WriteStream);
 };
 
 
 // Reads a snapshot into objects.
 class SnapshotReader {
  public:
   SnapshotReader(const Snapshot* snapshot,
                  Heap* heap,
                  ObjectStore* object_store)
@@ skipping 211 matching lines @@
 
  private:
   SnapshotWriter* writer_;
 
   DISALLOW_COPY_AND_ASSIGN(SnapshotWriterVisitor);
 };
 
 }  // namespace dart
 
 #endif  // VM_SNAPSHOT_H_