These instructions aren't implemented yet in TF or in Liftoff, but they
are properly decoded.

The table instructions (i.e. `table.{init,drop,copy}`) are validated,
since the table and element sections occur before the code section. The
memory instructions (i.e. `memory.{init,drop,copy,fill}`) are not
validated because the data section occurs after the code section, so it
can't be verified in one pass (without throwing a validation error
later).

There is currently a discussion about whether to add a new section
(similar to `func`) that predefines the number of expected data
segments. If we add this, then we can validate in one pass. For now,
we'll leave it unimplemented.

Bug: v8:7747
Change-Id: I839edf51721105a47a1fa8dd5e5e1bd855e72447
Reviewed-on: https://chromium-review.googlesource.com/c/1339241
Commit-Queue: Ben Smith <binji@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57622}