With the introduction of a jump table, call targets will not be
{WasmCode} objects any more. Instead, we just call any {Address}.
This CL does not change anything yet, but changes interfaces to accept
an {Address} instead of {WasmCode*}.

R=titzer@chromium.org

Bug: v8:7758
Change-Id: Id299738bb7cc6a1891e4a03d7f67c24cde6d1699
Reviewed-on: https://chromium-review.googlesource.com/1058793
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53191}