[wasm] Rename regression test to follow convention

R=eholk@chromium.org

Bug: chromium:769637
Change-Id: I347ed1cf6fe567f5a12a8191b224a27336a757d4
Reviewed-on: https://chromium-review.googlesource.com/1000700Reviewed-by: Eric Holk <eholk@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52493}