There's a bug in OS X 10.11 where a toll-free bridged font may have an
attributed of private class __NSCFCharacterSet that unlike
NSCharacterSet doesn't conform to NSSecureCoding. This poses a problem
when such font is used in user-editable content, because some Asian
input methods then crash in 10.11 when editing the string. As a
workaround for this bug, don't use toll-free bridging, but re-create
NSFont from the descriptor instead on buggy OS X versions.
Fixes regression introduced in a77066d530
(#507).
926d486f54