Extract non-IO part of mksnapshot into an API method.

src/snapshot-source-sink.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_SNAPSHOT_SOURCE_SINK_H_
 #define V8_SNAPSHOT_SOURCE_SINK_H_
 
 #include "src/base/logging.h"
 #include "src/utils.h"
 
@@ skipping 73 matching lines @@
 
   void Put(byte b, const char* description) { data_.Add(b); }
 
   void PutSection(int b, const char* description) {
     DCHECK_LE(b, kMaxUInt8);
     Put(static_cast<byte>(b), description);
   }
 
   void PutInt(uintptr_t integer, const char* description);
   void PutRaw(const byte* data, int number_of_bytes, const char* description);
-  void PutBlob(Vector<const byte> blob, const char* description);
   int Position() { return data_.length(); }
 
   const List<byte>& data() const { return data_; }
 
  private:
   List<byte> data_;
 };
 
 }  // namespace v8::internal
 }  // namespace v8
 
 #endif  // V8_SNAPSHOT_SOURCE_SINK_H_