Ensure that {min} is smaller than {max}, and auto-compute {max} as
{arraysize(data)}.
We had two tests which did not actually test anything.

This is the second CL in a series to improve our module decoder tests
and make them more readable.

R=titzer@chromium.org

Bug: v8:8238
Change-Id: Ie467fa54609bc5fd860608085a2d58ed8341f5e7
Reviewed-on: https://chromium-review.googlesource.com/c/1282956Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56703}