hasClass
Checks to see if method@GutterLines.add_class was called with the @name for @line.
A faster version of this function is provided via method@GutterLines.has_qclass for situations where the quark is known ahead of time.
Return
true if @line contains @name
Parameters
line
a line number starting from zero
name
a class name that may be converted, to a #GQuark