Also show history timeline for test results on Android (and not only desktop)

[whimboo]

We run the web-platform tests on Android devices for both Chrome and Firefox, and the results are already visible, as shown in the following URL:

https://wpt.fyi/results/webdriver/tests/classic/new_session/websocket_url.py?label=experimental&label=master&product=firefox&product=firefox_android&product=chrome&product=chrome_android&product=safari&aligned&view=subtest

However, the history timeline, which you can access by clicking the "Show history timeline" button at the bottom, only displays the history for desktop platforms and not for mobile. It would be incredibly helpful for discovering flakiness and identifying regression ranges if the timeline also included Android results, or better yet, showed the history of test results for all selected browsers.

CC @jgraham @foolip