Till now, they were just skipped. With this patch, they now show up in
the DevTools on uncaught Errors with function name <WASM> and no line
number or file name information (see new test case:
https://chromiumcodereview.appspot.com/1875083002).

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

Review URL: https://codereview.chromium.org/1865553004

Cr-Commit-Position: refs/heads/master@{#35615}