GitLab

- Autogenerate Polymer 3 version of cr-search-field and its automated
tests
- Add to Polymer 3 demo page

Bug: 965770
Change-Id: I6901db78e71767f757642aa89dae43be4473dd33
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1786177Reviewed-by: Esmael Elmoslimany <aee@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#693917}