* FIX: Better virtual keyboard detect on Android
Firefox has a bug where *sometimes* the visualViewport.height won't be
updated when the keyboard pops up until you scroll, making our composer
stay hidden behind the keyboard. This commit uses both window.innerHeight
and window.visualViewport.height using the minimum of both to check for
height changes.
For Chrome/Edge we feature detect the new VirtualKeyboard API and
opt-into it when the composer opens and use it to detect if a keyboard
is being draw. Opting into the API changes how the viewport is
calculated so we have to also change how the full height composer is
calculated. To minimize breakage we opt-out when the composer component
is destroyed.
This commit also moves the `--composer-ipad-padding` to only happen on
iPads.
Bug report at https://meta.discourse.org/t/-/228382
ab58b0cffe