This fixes a corner-case with lazy compilation in WebAssembly where
native-heap code did not expect to see WASM-to-JS wrappers in tables.

R=clemensh@chromium.org
TEST=mjsunit/regress/wasm/regress-803788
BUG=chromium:803788

Change-Id: Ie44b5c9efe2b171e1915295bb95d6cb61dfab3dc
Reviewed-on: https://chromium-review.googlesource.com/878262Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50755}