The new fuzzer takes the fuzzer input as module bytes and compiles them
with WebAssembly asynchronous compilation.

R=mtrofin@chromium.org

Change-Id: I9740edec68e26c04d011d85c68521e340be13c4c
Reviewed-on: https://chromium-review.googlesource.com/506156
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Mircea Trofin <mtrofin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45912}