R=titzer@chromium.org
TEST=mjsunit/wasm/exceptions-rethrow,unittests/FunctionBodyDecoderTest
BUG=v8:8091

Change-Id: If52be505fb9897af1bd59d17d1ab47b33b665be0
Reviewed-on: https://chromium-review.googlesource.com/c/1273050
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56563}