deps: backport bits of 9302db480e8 from upstream V8

Backport parts of v8/v8@9302db480e8cd7c88fd948baf0cf that fix
compiler errors on Windows.

Original commit message:

    [ubsan] Port HeapObject to the new design

    Merging the temporary HeapObjectPtr back into HeapObject.

    Bug: v8:3770
    Change-Id: I5bcd23ca2f5ba862cf5b52955dca143e531c637b
    Reviewed-on: https://chromium-review.googlesource.com/c/1386492
    Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
    Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
    Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
    Reviewed-by: Michael Stanton <mvstanton@chromium.org>
    Reviewed-by: Jakob Gruber <jgruber@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#58410}

Refs: v8/v8@9302db4

deps/v8/src/ia32/assembler-ia32-inl.h

@@ -109,7 +109,7 @@ void RelocInfo::set_target_object(Heap* heap, HeapObject* target,
   if (icache_flush_mode != SKIP_ICACHE_FLUSH) {
     Assembler::FlushICache(pc_, sizeof(Address));
   }
-  if (write_barrier_mode == UPDATE_WRITE_BARRIER && host() != nullptr) {
+  if (write_barrier_mode == UPDATE_WRITE_BARRIER && !host().is_null()) {
     WriteBarrierForCode(host(), this, target);
   }
 }
@@ -279,7 +279,8 @@ Address Assembler::target_address_from_return_address(Address pc) {
 void Assembler::deserialization_set_special_target_at(
     Address instruction_payload, Code code, Address target) {
   set_target_address_at(instruction_payload,
-                        code ? code->constant_pool() : kNullAddress, target);
+                        !code.is_null() ? code->constant_pool() : kNullAddress,
+                        target);
 }
 
 int Assembler::deserialization_special_target_size(