Do not rewrite the VM isolate's symbol table during AOT snapshots.

runtime/vm/clustered_snapshot.h

 // Copyright (c) 2016, 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 RUNTIME_VM_CLUSTERED_SNAPSHOT_H_
 #define RUNTIME_VM_CLUSTERED_SNAPSHOT_H_
 
 #include "platform/assert.h"
 #include "vm/allocation.h"
 #include "vm/bitfield.h"
@@ skipping 359 matching lines @@
   intptr_t next_index() const { return next_ref_index_; }
   Heap* heap() const { return heap_; }
   Snapshot::Kind kind() const { return kind_; }
 
  private:
   Heap* heap_;
   Zone* zone_;
   Snapshot::Kind kind_;
   ReadStream stream_;
   InstructionsReader* instructions_reader_;
+  intptr_t num_base_objects_;
   intptr_t num_objects_;
   intptr_t num_clusters_;
   RawArray* refs_;
   intptr_t next_ref_index_;
   DeserializationCluster** clusters_;
 };
 
 
 class FullSnapshotWriter {
  public:
@@ skipping 71 matching lines @@
   intptr_t size_;
   const uint8_t* instructions_buffer_;
   const uint8_t* data_buffer_;
 
   DISALLOW_COPY_AND_ASSIGN(FullSnapshotReader);
 };
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_CLUSTERED_SNAPSHOT_H_