Throwing an object that needs special property lookup currently traps
when we catch it in wasm. We should just return undefined to let the
caller know that this is not a wasm exception object.

Drive-by: use the named {caught_tag} register consistently.

R=clemensb@chromium.org

Bug: chromium:1188825
Change-Id: I8ebd4db756ac7ba04208ab43c7349c28b813fc49
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2767519Reviewed-by: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73497}