This reads much nicer than the for loop with {num_imported_functions_}
and {num_functions}, and is potentially even faster, because we access
the code table directly and not via function index.

R=mstarzinger@chromium.org

Bug: v8:7754
Change-Id: I83e5c0253d8f78c22982a79d878431ba75cfc027
Reviewed-on: https://chromium-review.googlesource.com/1090271Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53574}