GitLab

- Autogenerate Polymer 3 versions for files in appearance_page/*
- Update closure compiler and polymer_modulizer/js_modulizer targets for
  these files
- Autogenerate tests for the Polymer 3 files.

Bug: 1026426
Change-Id: If58ea84995634c223b6e37af3e0c721461f9f63e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2045038
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#740398}