[frontend/qml] Use wheel.pixelDelta if it's available.
[frontend/qml] Use wheel.pixelDelta if it's available.

Fallback to wheel.angleDelta.
Close #428.

farhaanbukhsh/lime,farhaanbukhsh/lime,crr0004/lime,crr0004/lime,crr0004/lime,crr0004/lime,farhaanbukhsh/lime,farhaanbukhsh/lime,crr0004/lime,farhaanbukhsh/lime