addClass/removeClass/toggleClass: add array as a valid argument

[timmywil]

See jquery/jquery#3532

jQuery 3.3 introduces a new signature to these methods, allowing a single array of strings to be passed as the first/only argument.

Note: .removeClass( [] ) will not remove all classes. It is instead equivalent to .removeClass( "" ). Passing no arguments (e.g. .removeClass()) will remove all classes.