This reverts commit dbfdd4f9.

Reason for revert: https://clusterfuzz.com/v2/testcase-detail/5493096547876864?noredirect=1

Original change's description:
> [heap] Turn on v8_enable_csa_write_barrier
> 
> With this commit, write barrier is switched to use CodeStubAssembler.
> 
> Bug: chromium:749486
> Change-Id: I7e0914bee971e4f3a3257740ae7c83b31f791bd9
> Reviewed-on: https://chromium-review.googlesource.com/598088
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Commit-Queue: Albert Mingkun Yang <albertnetymk@google.com>
> Cr-Commit-Position: refs/heads/master@{#48006}

TBR=ulan@chromium.org,albertnetymk@google.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: chromium:749486
Change-Id: I8cf6a3f1d2ea607a0160b37b797d743b88b004b5
Reviewed-on: https://chromium-review.googlesource.com/667018Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Albert Mingkun Yang <albertnetymk@google.com>
Cr-Commit-Position: refs/heads/master@{#48036}