add patch to speed up V8 snapshot deserialization

Two optimizations targeting the hot deserialization loop:

1. Skip write barriers during non-user-code deserialization. During
   startup/shared-heap/context deserialization all objects are allocated
   in old space and incremental marking is not active, so every write
   barrier is a guaranteed no-op — but each still pays ~8 instructions
   of MemoryChunk lookups and branch checks per slot write.

2. Compile out trace_deserialization flag checks from the hot bytecode
   dispatch loop (31 occurrences). Replace with TRACE_DESER macros that
   compile to nothing unless V8_ENABLE_TRACE_DESERIALIZATION is defined,
   reducing icache pressure in ReadSingleBytecodeData.

Author: bartlomieju