Clean up the data for navigator.getBattery() (#9626)

Summary of changes:
 - Remove navigator.battery, which has been removed since 2013/2016 in
   Chrome and Firefox respectively.
 - Treat BatteryManager as only supported since navigator.getBattery()
   was supported, making the data consistent but technically wrong.
 - Simplify Firefox support to only represent when it was on by default
   for web content. Flags before that and chrome-only after is removed.
 - Remove claims of prefixes on BatteryManager, the only prefixes here
   have been navigator.mozBattery and navigator.webkitBattery.
 - Don't claim it's deprecated, https://w3c.github.io/battery/ is still
   a "real" spec and Chromium hasn't deprecated it.
 - Scope the chargingTime/dischargingTime notes to just those entries,
   and treat it as fixed in Chromium 42 (see below).

The chargingTime/dischargingTime issue was fixed in Chromium 42:
https://bugs.chromium.org/p/chromium/issues/detail?id=401553
https://storage.googleapis.com/chromium-find-releases-static/13e.html#13e397e55501bee3903bfe46edfd56f2442c1f11

Data originally from #1102.
There was no evidence for or discussion on the webview_android version
being 40. All existing versions were treated as untrustworthy and data
was mirrored to all Chromium browsers.