Serializer: ensure unique script ids when deserializing.

src/heap/heap.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_HEAP_HEAP_H_
 #define V8_HEAP_HEAP_H_
 
 #include <cmath>
 
 #include "src/allocation.h"
@@ skipping 1331 matching lines @@
 
   // The roots that have an index less than this are always in old space.
   static const int kOldSpaceRoots = 0x20;
 
   uint32_t HashSeed() {
     uint32_t seed = static_cast<uint32_t>(hash_seed()->value());
     DCHECK(FLAG_randomize_hashes || seed == 0);
     return seed;
   }
 
+  Smi* NextScriptId() {
+    int next_id = last_script_id()->value() + 1;
+    if (!Smi::IsValid(next_id) || next_id < 0) next_id = 1;
+    Smi* next_id_smi = Smi::FromInt(next_id);
+    set_last_script_id(next_id_smi);
+    return next_id_smi;
+  }
+
   void SetArgumentsAdaptorDeoptPCOffset(int pc_offset) {
     DCHECK(arguments_adaptor_deopt_pc_offset() == Smi::FromInt(0));
     set_arguments_adaptor_deopt_pc_offset(Smi::FromInt(pc_offset));
   }
 
   void SetConstructStubDeoptPCOffset(int pc_offset) {
     DCHECK(construct_stub_deopt_pc_offset() == Smi::FromInt(0));
     set_construct_stub_deopt_pc_offset(Smi::FromInt(pc_offset));
   }
 
@@ skipping 1256 matching lines @@
   DisallowHeapAllocation no_allocation;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_HEAP_H_