widget: Only deny a sequence if it was previously claimed

widget: Only deny a sequence if it was previously claimed

Before this change, a sequence being claimed deep in the event propagation
chain would make the sequence go denied on every ancestor, regardless of
previous state.

To make things more consistent, only deny the sequence if it was previously
claimed, so the behavior is the same for gesture groups within the widget
than for those outside the widget.

The gestures testsuite has been updated to reflect this new behavior.