GitLab

 - Fix a bug in route.js where pageVisibility is undefined in
   Polymer 3.
 - Fix a newly found type-check error in
   global_scroll_target_begavior.js (only happens in the context
   of a JS module).
 - Update search_engines_page/ prod and test code as needed.
 - Update BUILD.gn, grdp files as needed.

Bug: 1026426
Change-Id: Ic2229bebdca80d08189943fabd62e1d86f050a2e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2032669
Commit-Queue: Demetrios Papadopoulos <dpapad@chromium.org>
Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#738448}