Temporary fix to allow running gcmole on isolate.cc

Bug: v8:12676
Change-Id: I0b625e6e0419885cf20758f22d897dc2532c2606
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3497335
Auto-Submit: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79347}