GestureRecognizer cleanup

Summary

Context

Description of change

Migration guide

Timeline

References

Summary

OneSequenceGestureRecognizer.addAllowedPointer() was changed to take a
PointerDownEvent, like it superclass. Previously, it accepted the more
general PointerEvent type, which was incorrect.

Context

The framework only ever passes PointerDownEvent objects to
addAllowedPointer(). Declaring
OneSequenceGestureRecognizer.addAllowedPointer() to take the more general
type was confusing, and caused OneSequenceGestureRecognizer subclasses to
have to cast their argument to the right class.

Description of change

The previous declaration forced OneSequenceGestureRecognizer descendants to
override addAllowedPointer() like so:

class

CustomGestureRecognizer

extends

ScaleGestureRecognizer

@override