…#176) (ionic-team#399)

- We only need the KeyboardWillHide event to fix this problem, and we only need it for ios 11+
- Enable the fix for ios 11+, not only ios 12+. It was probably only 12+ because no devices have a max OS of 11, so no dev probably confirmed the problem's existence (or non-existence) on 11, myself included.  (But the functionality that started this issue chain began in ios 11.)
- Do some math to make sure the offset when the keyboard goes down doesn't result in empty white space being displayed.
- This solution can potentially be removed when apple finally releases the fix for the issue discussed here: apache/cordova-ios#417 (comment)
For full details see PR ionic-team#532

…e in ios 13.4 Apple fixed the problem.

See ionic-team#533 (comment)