[serializer] Add API to warm up startup snapshot with an additional script.

src/isolate.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_ISOLATE_H_
 #define V8_ISOLATE_H_
 
 #include <queue>
 #include <set>
 
@@ skipping 1340 matching lines @@
   friend class ThreadManager;
   friend class Simulator;
   friend class StackGuard;
   friend class ThreadId;
   friend class TestMemoryAllocatorScope;
   friend class TestCodeRangeScope;
   friend class v8::Isolate;
   friend class v8::Locker;
   friend class v8::Unlocker;
   friend v8::StartupData v8::V8::CreateSnapshotDataBlob(const char*);
+  friend v8::StartupData v8::V8::WarmUpSnapshotDataBlob(v8::StartupData,
+                                                        const char*);
 
   DISALLOW_COPY_AND_ASSIGN(Isolate);
 };
 
 
 #undef FIELD_ACCESSOR
 #undef THREAD_LOCAL_TOP_ACCESSOR
 
 
 class PromiseOnStack {
@@ skipping 195 matching lines @@
 
   EmbeddedVector<char, 128> filename_;
   FILE* file_;
   int scope_depth_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_ISOLATE_H_