[ptr-compr] Don't use Code::cast for off-heap code objects

because attempt to decompress the off-heap map slot will fail.

Bug: v8:7703
Change-Id: Iad3884fb95ccb17b2992d190acb5914062a0e8f4
Reviewed-on: https://chromium-review.googlesource.com/c/1365286Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58076}

src/snapshot/serializer.cc

@@ -309,7 +309,9 @@ Code Serializer::CopyCode(Code code) {
   code_buffer_.insert(code_buffer_.end(),
                       reinterpret_cast<byte*>(code->address()),
                       reinterpret_cast<byte*>(code->address() + size));
-  return Code::cast(HeapObject::FromAddress(
+  // When pointer compression is enabled the checked cast will try to
+  // decompress map field of off-heap Code object.
+  return Code::unchecked_cast(HeapObject::FromAddress(
       reinterpret_cast<Address>(&code_buffer_.front())));
 }