Even though IsWasmCompileAllowed function in runtime/runtime-test.cc can
be invoked only when native calls are allowed, so this is not an
actual bug, fuzzing or random testing can call this function and make a
false positive. Thus, add a checking if the given argument is actually
an array buffer.

Bug: v8:5981
Change-Id: I3918c4d68b67a507c93865effa490d7259d63cb1
Reviewed-on: https://chromium-review.googlesource.com/732383Reviewed-by: Mircea Trofin <mtrofin@chromium.org>
Commit-Queue: Mircea Trofin <mtrofin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50116}