This reverts commit 1feadfe8.

Reason for revert: Reland as bot stayed red after revert.

Original change's description:
> Revert "[cctest] Clarify that tests for sync instructions are simulator specific"
> 
> This reverts commit 4013518f.
> 
> Reason for revert:
> https://build.chromium.org/p/client.v8.ports/builders/V8%20Linux%20-%20arm64%20-%20sim%20-%20gc%20stress
> 
> Original change's description:
> > [cctest] Clarify that tests for sync instructions are simulator specific
> > 
> > Some tests were recently added to test-simulator-arm.cc, however this file is
> > meant for tests that are specific to the simulator and therefore are not written
> > to work on hardware. While this sounds surprising, the reason is that our simulation
> > of synchronisation instructions is more conservative than on hardware.
> > 
> > To make this more clear, this patch renames the "test-simulator-arm{,64}.cc"
> > files to "test-sync-primitives-arm{,64}.cc", and moves the vneg and vabs tests
> > into "test-assembler-arm.cc" which is were tests that are garanteed to work in
> > either native or simulated environments live.
> > 
> > Finally, take the opportunity to share a little bit of code.
> > 
> > Bug: v8:6963
> > Change-Id: Ifb85d3671c823b9bba73d09f419536b089a4e87c
> > Reviewed-on: https://chromium-review.googlesource.com/749387
> > Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
> > Commit-Queue: Pierre Langlois <pierre.langlois@arm.com>
> > Cr-Commit-Position: refs/heads/master@{#49073}
> 
> TBR=clemensh@chromium.org,pierre.langlois@arm.com,bmeurer@chromium.org
> 
> Change-Id: I1bfb4e9c7c18b716f417a84b18a14cb2e1fa3a7a
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: v8:6963
> Reviewed-on: https://chromium-review.googlesource.com/750624
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Commit-Queue: Michael Achenbach <machenbach@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#49074}

TBR=machenbach@chromium.org,clemensh@chromium.org,pierre.langlois@arm.com,bmeurer@chromium.org

Change-Id: I5af7bd3678758130534730a2f6f0b651b64c6956
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:6963
Reviewed-on: https://chromium-review.googlesource.com/750903Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49075}