When deduplicating program metadata, try to use objects from the VM isolate.

runtime/vm/dart.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 RUNTIME_VM_DART_H_
 #define RUNTIME_VM_DART_H_
 
 #include "include/dart_api.h"
 #include "vm/allocation.h"
 #include "vm/snapshot.h"
@@ skipping 58 matching lines @@
   static DebugInfo* pprof_symbol_generator() { return pprof_symbol_generator_; }
 
   static LocalHandle* AllocateReadOnlyApiHandle();
   static bool IsReadOnlyApiHandle(Dart_Handle handle);
 
   static uword AllocateReadOnlyHandle();
   static bool IsReadOnlyHandle(uword address);
 
   static const char* FeaturesString(Isolate* isolate, Snapshot::Kind kind);
   static Snapshot::Kind vm_snapshot_kind() { return vm_snapshot_kind_; }
+  static const uint8_t* vm_snapshot_instructions() {
+    return vm_snapshot_instructions_;
+  }
+  static void set_vm_snapshot_instructions(const uint8_t* buffer) {
+    vm_snapshot_instructions_ = buffer;
+  }
 
   static Dart_ThreadExitCallback thread_exit_callback() {
     return thread_exit_callback_;
   }
   static void set_thread_exit_callback(Dart_ThreadExitCallback cback) {
     thread_exit_callback_ = cback;
   }
   static void SetFileCallbacks(Dart_FileOpenCallback file_open,
                                Dart_FileReadCallback file_read,
                                Dart_FileWriteCallback file_write,
@@ skipping 27 matching lines @@
  private:
   static void WaitForIsolateShutdown();
   static void WaitForApplicationIsolateShutdown();
 
   static Isolate* vm_isolate_;
   static int64_t start_time_micros_;
   static ThreadPool* thread_pool_;
   static DebugInfo* pprof_symbol_generator_;
   static ReadOnlyHandles* predefined_handles_;
   static Snapshot::Kind vm_snapshot_kind_;
+  static const uint8_t* vm_snapshot_instructions_;
   static Dart_ThreadExitCallback thread_exit_callback_;
   static Dart_FileOpenCallback file_open_callback_;
   static Dart_FileReadCallback file_read_callback_;
   static Dart_FileWriteCallback file_write_callback_;
   static Dart_FileCloseCallback file_close_callback_;
   static Dart_EntropySource entropy_source_callback_;
 };
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_DART_H_