This CL makes the names of tracing flags related to WASM consistent
with the rest of V8 tracing flags.

R=ahaas@chromium.org

Change-Id: I871fb7b5e27ff7b8f587e08507d15c0719881990
Reviewed-on: https://chromium-review.googlesource.com/1193182
Commit-Queue: Ben Titzer <titzer@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55479}