The constructor taking an Isolate and HeapObject never uses the
HeapObject value and just calls through to the Isolate constructor.

Bug: v8:9810
Change-Id: Ia2553b4d1f31cf24549980dbb5c2bfa38fe91f8c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1918247
Auto-Submit: Dan Elphick <delphick@chromium.org>
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64986}