Tweak memory management in the serializer.

src/serialize.h

Index: src/serialize.h
diff --git a/src/serialize.h b/src/serialize.h
index 415d54244e7dd1b787f480fed7d1e41c33de2d29..6817c7efe6922910025c604d36584af985c75cb5 100644
--- a/src/serialize.h
+++ b/src/serialize.h
@@ -703,6 +703,8 @@ class Serializer : public SerializerDeserializer {
     // External strings are serialized in a way to resemble sequential strings.
     void SerializeExternalString();
 
+    Address PrepareCode();
+
     Serializer* serializer_;
     HeapObject* object_;
     SnapshotByteSink* sink_;
@@ -749,6 +751,8 @@ class Serializer : public SerializerDeserializer {
   // of the serializer.  Initialize it on demand.
   void InitializeCodeAddressMap();
 
+  Code* CopyCode(Code* code);
+
   inline uint32_t max_chunk_size(int space) const {
     DCHECK_LE(0, space);
     DCHECK_LT(space, kNumberOfSpaces);
@@ -783,6 +787,8 @@ class Serializer : public SerializerDeserializer {
   uint32_t large_objects_total_size_;
   uint32_t seen_large_objects_index_;
 
+  List<byte> code_buffer_;
+
   DISALLOW_COPY_AND_ASSIGN(Serializer);
 };