Fix compilation failure due to overload of virtual function

test/mkgrokdump/mkgrokdump.cc

 // 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.
 
 #include <stdio.h>
 
 #include "include/libplatform/libplatform.h"
 #include "include/v8.h"
 
 #include "src/frames.h"
@@ skipping 19 matching lines @@
 #if defined(V8_USE_SNAPSHOT) && !defined(DEBUG)
 static const char* kBuild = "shipping";
 #else
 static const char* kBuild = "non-shipping";
 #endif
 
 class MockArrayBufferAllocator : public v8::ArrayBuffer::Allocator {
  public:
   void* Allocate(size_t length) override { return nullptr; }
   void* AllocateUninitialized(size_t length) override { return nullptr; }
+  void* Reserve(size_t length) override { return nullptr; }
+  void Free(void* data, size_t length, AllocationMode mode) override {}
   void Free(void* p, size_t) override {}
+  void SetProtection(void* data, size_t length,
+                     Protection protection) override {}
 };
 
 static int DumpHeapConstants(const char* argv0) {
   // Start up V8.
   v8::Platform* platform = v8::platform::CreateDefaultPlatform();
   v8::V8::InitializePlatform(platform);
   v8::V8::Initialize();
   v8::V8::InitializeExternalStartupData(argv0);
   Isolate::CreateParams create_params;
   MockArrayBufferAllocator mock_arraybuffer_allocator;
@@ skipping 73 matching lines @@
   // Teardown.
   isolate->Dispose();
   v8::V8::ShutdownPlatform();
   delete platform;
   return 0;
 }
 
 }  // namespace v8
 
 int main(int argc, char* argv[]) { return v8::DumpHeapConstants(argv[0]); }