The wasm module we generate for the test case actually has an initial
memory size of 16. In the mjsunit test we generate, however, we set the
initial memory size to 32. This CL changes the initial memory size in
the mjsunit test now to 16.

R=eholk@chromium.org

Change-Id: I5d3a30a97c3b0ba3105a8cf17d4c088a8fb9c8b7
Reviewed-on: https://chromium-review.googlesource.com/436544
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#42915}