This flips the section codes for the exception section (part of the
exception handling proposal) and the data-count section (part of the
bulk memory proposal).

Also see the following discussions for the underlying motivation:
https://github.com/WebAssembly/bulk-memory-operations/pull/42
https://github.com/WebAssembly/exception-handling/issues/70

R=binji@chromium.org
BUG=v8:8868

Change-Id: I9f5f524e7aec067720346a5bb8d45c7c80a4c7a2
Reviewed-on: https://chromium-review.googlesource.com/c/1478207Reviewed-by: Ben Smith <binji@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59856}