Add #add(position, index) to ListModelBase.

Change-Id: I81198806879df502bc3eb1b7522330c3c4a82805
Reviewed-on: https://chromium-review.googlesource.com/c/1491553
Commit-Queue: Jordan Demeulenaere <jdemeulenaere@chromium.org>
Reviewed-by: Theresa <twellington@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636066}
1 file changed