The maps in question are already processed in
NativeContextData::Serialize.

R=jarin@chromium.org

Bug: v8:7790
Change-Id: Ifbbff64e10458605b09c74fe09e574b2f2659839
Reviewed-on: https://chromium-review.googlesource.com/c/1317809
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57247}