[ChromeDriver] Update tests to use v1 shadow DOM

Chrome will stop supporting v0 shadow DOM. Updating ChromeDriver Python
tests to use v1 shadow DOM instead. Also cleaning up some obsolete HTML
code.

Bug: chromedriver:2729
Change-Id: Ifc142958e9a3c29ad9aa225aaaed017f9632cd46
Reviewed-on: https://chromium-review.googlesource.com/c/1413374
Reviewed-by: Caleb Rouleau <crouleau@chromium.org>
Commit-Queue: John Chen <johnchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#622910}
2 files changed