Fix issue 571: display descriptive names for code objects from snapshot.

src/snapshot-common.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 61 matching lines @@
   virtual ~FileByteSink() {
     if (fp_ != NULL) {
       fclose(fp_);
     }
   }
   virtual void Put(int byte, const char* description) {
     if (fp_ != NULL) {
       fputc(byte, fp_);
     }
   }
+  virtual int Position() {
+    return ftell(fp_);
+  }
 
  private:
   FILE* fp_;
 };
 
 
 bool Snapshot::WriteToFile(const char* snapshot_file) {
   FileByteSink file(snapshot_file);
   Serializer ser(&file);
   ser.Serialize();
   return true;
 }
 
 
 
 } }  // namespace v8::internal