Since traps now throw real Error objects, we get stack traces
containing <WASM> functions on top-level. The additional tests check
for two traps: unreachable and memory out-of-bounds.

R=ahaas@chromium.org, jfb@chromium.org, titzer@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1878563003

Cr-Commit-Position: refs/heads/master@{#35691}