Delay completing marking (and thus the atomic GC pause) during JS
executions, increasing the chance to finalize the garbage collection
from a task. This is beneficial as it avoids stack scanning which is
expensive and can keep alive outdated objects in case of unified heap.

Completing will be delayed at most by some overshoot factor (10%).

In addition, the GC keeps the weighted average of previously recorded
time to incremental marking task invocations and bails out if the
task is expected to arrive too late.

Reland: Do not schedule a delayed task when marking has already been
finalized.

This reverts commit 1775684e.

Bug: chromium:1044630, v8:10178
Change-Id: Ic46e9504ce7c200bd1d37ee8d0190fb8727a3f96
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2037436Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66137}