Note that this also renames the existing "asm_wasm" variant to use the
more appropriate "stress_asm_wasm" name.

R=rmcilroy@chromium.org
BUG=v8:6409

Cq-Include-Trybots: master.tryserver.v8:v8_linux_noi18n_rel_ng
Change-Id: I1f9550cd03874c678f4583047a4e123a6f090250
Reviewed-on: https://chromium-review.googlesource.com/584879
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46937}