Passing an isolate to {RecompileNativeModule} feels wrong, since
compilation and the generated code are totally isolate-independent. In
fact, the isolate is only used for updating counters.
Instead of passing the counters instead, this CL just refactors the code
to support a nullptr for the counters everywhere (some code paths
already supported that). The few recompilation would not make a
significant difference in the histograms anyway, and even have the risk
of skewing the data.

Drive-by 1: Rename {TierUp} to {StartTierUp} and update comments.
Drive-by 2: Remove non-actionable TODO.

R=thibaudm@chromium.org

Bug: v8:10359
Change-Id: Ic027f939bbc55398b90784922130fe1fe5573b0c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2187638Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67708}