This CL does attempt to modify Map Panel to ensure it follows web
component standards.

Change-Id: I1432d536d77233b6b8c45ff92dc8aba127f93510
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2276044Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
Commit-Queue: Sathya Gunasekaran  <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68647}