Handle screen rotation

[MrEricSir]

The Android version doesn't respond to screen rotation correctly.

• If the screen is rotated while a dialog is open, the webview is not resized.
• When the screen is rotated, the height of the webview needs to be re-sent to the javascript layer

[MrEricSir]

I think I've narrowed this down to a bug in Qt, which I've filed here: https://bugreports.qt.io/browse/QTBUG-47039