This is a reland of a4105a43

Original change's description:
> [wasm] Implement handling of exported/imported exceptions.
> 
> This implements the proper semantics for matching exported/imported
> exceptions by using the notion of an "exception tag" that is global to
> the system. It can be used to match exceptions in one module against
> exceptions declared and/or thrown in another module (or instance).
> 
> R=clemensh@chromium.org
> TEST=mjsunit/wasm/exceptions-shared
> BUG=v8:8091
> 
> Change-Id: I37586d7be5d5e6169b3418dfbc415b26dd4750dd
> Reviewed-on: https://chromium-review.googlesource.com/1226976
> Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
> Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#55940}

Bug: v8:8091
Change-Id: Ib85f099b26a8323a8a00299b5aaeb05aaff3c3c6
Reviewed-on: https://chromium-review.googlesource.com/1227975Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55959}