Expose the ValueSerializer data format version as a compile-time constant.

include/v8-value-serializer-version.h

Index: include/v8-value-serializer-version.h
diff --git a/include/v8-value-serializer-version.h b/include/v8-value-serializer-version.h
new file mode 100644
index 0000000000000000000000000000000000000000..c72911c64dc571cd5c3a4d009833d80028e13d46
--- /dev/null
+++ b/include/v8-value-serializer-version.h
@@ -0,0 +1,24 @@
+// Copyright 2017 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.
+
+/**
+ * Compile-time constants.
+ *
+ * This header provides access to information about the value serializer at
+ * compile time, without declaring or defining any symbols that require linking
+ * to V8.
+ */
+
+#ifndef INCLUDE_V8_VALUE_SERIALIZER_VERSION_H_
+#define INCLUDE_V8_VALUE_SERIALIZER_VERSION_H_
+
+#include <stdint.h>
+
+namespace v8 {
+
+constexpr uint32_t CurrentValueSerializerFormatVersion() { return 13; }
+
+}  // namespace v8
+
+#endif  // INCLUDE_V8_VALUE_SERIALIZER_VERSION_H_