Fix compilation warnings/errors seen with newer versions of gcc compiler.

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"
 
 namespace dart {
 
 // Forward declarations.
 class DebugInfo;
 class Isolate;
 
 class Dart : public AllStatic {
  public:
   static bool InitOnce(int argc, char** argv,
                        Dart_IsolateInitCallback callback);
 
-  static Isolate* CreateIsolate(void* snapshot, void* data);
+  static Isolate* CreateIsolate(const Dart_Snapshot* snapshot, void* data);
   static void ShutdownIsolate();
 
   static Isolate* vm_isolate() { return vm_isolate_; }
 
   static void set_pprof_symbol_generator(DebugInfo* value) {
     pprof_symbol_generator_ = value;
   }
   static DebugInfo* pprof_symbol_generator() { return pprof_symbol_generator_; }
 
  private:
   static Isolate* vm_isolate_;
   static DebugInfo* pprof_symbol_generator_;
 };
 
 }  // namespace dart
 
 #endif  // VM_DART_H_