This checks the type signature during import against the expected
signature. For this the {WasmExceptionObject} now contains a serialized
version of the signature.

R=clemensh@chromium.org
TEST=mjsunit/wasm/exceptions-import
BUG=v8:8091

Change-Id: I5a34ef87eccf4d2ed3a784620796ec009623fd90
Reviewed-on: https://chromium-review.googlesource.com/1219509Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55789}