[torque] Dehandlify torque generated initializers

Bug: v8:11263
Change-Id: I4d7d614666ff846740e1bfc1146bd82f08f6a739
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3420830Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78834}

src/torque/implementation-visitor.cc

@@ -4765,21 +4765,22 @@ void ImplementationVisitor::GenerateClassDefinitions(
         factory_impl << ");\n";
         factory_impl << "  Map map = factory()->read_only_roots()."
                      << SnakeifyString(type->name()) << "_map();";
-        factory_impl << "  HeapObject result =\n";
+        factory_impl << "  HeapObject raw_object =\n";
         factory_impl << "    factory()->AllocateRawWithImmortalMap(size, "
                         "allocation_type, map);\n";
+        factory_impl << "  " << type->UnhandlifiedCppTypeName()
+                     << " result = " << type->UnhandlifiedCppTypeName()
+                     << "::cast(raw_object);\n";
+        factory_impl << "  DisallowGarbageCollection no_gc;";
         factory_impl << "  WriteBarrierMode write_barrier_mode =\n"
                      << "     allocation_type == AllocationType::kYoung\n"
                      << "     ? SKIP_WRITE_BARRIER : UPDATE_WRITE_BARRIER;\n"
                      << "  USE(write_barrier_mode);\n";
-        factory_impl << "  " << type->HandlifiedCppTypeName()
-                     << " result_handle(" << type->name()
-                     << "::cast(result), factory()->isolate());\n";
 
         for (const Field& f : type->ComputeAllFields()) {
           if (f.name_and_type.name == "map") continue;
           if (!f.index) {
-            factory_impl << "  result_handle->TorqueGeneratedClass::set_"
+            factory_impl << "  result.TorqueGeneratedClass::set_"
                          << SnakeifyString(f.name_and_type.name) << "(";
             if (f.name_and_type.type->IsSubtypeOf(
                     TypeOracle::GetTaggedType()) &&
@@ -4793,7 +4794,7 @@ void ImplementationVisitor::GenerateClassDefinitions(
           }
         }
 
-        factory_impl << "  return result_handle;\n";
+        factory_impl << "  return handle(result, factory()->isolate());\n";
         factory_impl << "}\n\n";
 
         factory_impl << "template EXPORT_TEMPLATE_DEFINE(V8_EXPORT_PRIVATE) "