Now the embedder can instruct V8 to restore the initial heap limit
once the heap size drops below the given percentage of the heap limit.

Bug: chromium:922038
Change-Id: Ib668406c5d59c02b45a8eae7de96527ebc3f2b4d
Reviewed-on: https://chromium-review.googlesource.com/c/1411606
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58837}