Last snapshot bits to get working precompiled hello_world on x64.

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 VM_DART_H_
 #define VM_DART_H_
 
 #include "include/dart_api.h"
 #include "vm/allocation.h"
 
@@ skipping 36 matching lines @@
     pprof_symbol_generator_ = value;
   }
   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 uint8_t* instructions_snapshot_buffer() {
+    return instructions_snapshot_buffer_;
+  }
+  static void set_instructions_snapshot_buffer(const uint8_t* buffer) {
+    instructions_snapshot_buffer_ = buffer;
+  }
+  static bool IsRunningPrecompiledCode() {
+    return instructions_snapshot_buffer_ != NULL;
+  }
+
  private:
   static void WaitForIsolateShutdown();
 
   static Isolate* vm_isolate_;
   static ThreadPool* thread_pool_;
   static DebugInfo* pprof_symbol_generator_;
   static ReadOnlyHandles* predefined_handles_;
+  static const uint8_t* instructions_snapshot_buffer_;
 };
 
 }  // namespace dart
 
 #endif  // VM_DART_H_