Now that we have full fledged module instantiation,
keeping alive a second interface seems clunky.

Droping it and switching the tests.

BUG= https://code.google.com/p/v8/issues/detail?id=4203
TEST=test-asm-validator,asm-wasm,other wasm
R=titzer@chromium.org,aseemgarg@chromium.org
LOG=N

Review URL: https://codereview.chromium.org/1660083002

Cr-Commit-Position: refs/heads/master@{#33700}