heap: Fix comment on HeapObjectHeader layout

Tbr: haraken@chromium.org
No-try: true
Change-Id: Ib5fceb6ad910c69365234e4b2f40925a0510057d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1699602
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#676788}
1 file changed