PinchArea was releasing the mouse grab when all touches were
released, causing the mouse release event to not be propagated
to its parents, who were then unable to correct their state.
Remove this code and allow the normal event handlers to do their
thing.

Change-Id: I367772ca13546425fed4bed4438084bdf3c74dde
Reviewed-by: Michael Brasser <michael.brasser@nokia.com>