Attempting to use the "Provide a custom JSHint library file" preference with jshint.js version 2.5.10 results in the the following error in the dialog.
File is not a valid JSHint library
If I point it at a jshint.js version 2.5.6 I have (not the built-in one) it works, but 2.5.10 results in this error. Note this issue may not be new in 2.5.10, I haven't tried 2.5.7 - 2.5.9.