This removes the field in question to make it simpler to serialize and
deserialize modules without having to worry about the state of lazy
compilation. It is always possible to clone a non-anonymous builtin,
even without having this module-wide field.

R=clemensh@chromium.org
TEST=mjsunit/regress/wasm/regress-803427
BUG=chromium:803427

Change-Id: I72041e314eb6ee92859d45f1db0ed8500003edc4
Reviewed-on: https://chromium-review.googlesource.com/878581
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50771}