This reverts commit 822aef29.

Reason for revert: Makes getters-on-elements flaky on many bots. E.g.:
https://build.chromium.org/p/client.v8/builders/V8%20Linux/builds/16848/steps/Check%20-%20isolates%20%28flakes%29/logs/getters-on-elements

Bisected locally and tested with:
tools/run-tests.py --gn --variants=asm_wasm mjsunit/getters-on-elements --isolates --random-seed-stress-count=500

Original change's description:
> [compiler] Mark shared functions which have an optimization job
> 
> Marking shared functions for tier-up was optimizing the functions
> non-concurrently, to avoid the case where the same shared function is
> optimized concurrently by multiple JS functions. This was particularly a
> problem for small functions, which (if called in a loop) could get
> marked for optimisation quite quickly.
> 
> In this CL, the shared function is instead marked as having an active
> optimization job running, and these do not spawn a compilation job.
> 
> BUG=693590
> 
> Change-Id: I3df93fbf9cec7eda8229fcf416d7c429c06bec86
> Reviewed-on: https://chromium-review.googlesource.com/446836
> Commit-Queue: Leszek Swirski <leszeks@chromium.org>
> Reviewed-by: Michael Stanton <mvstanton@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#43778}

TBR=mvstanton@chromium.org,leszeks@chromium.org,hablich@chromium.org,v8-reviews@googlegroups.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=693590

Change-Id: If7dbdf3de302ec595c44e7f4795554db7674f22f
Reviewed-on: https://chromium-review.googlesource.com/454042Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43787}