maint: Remove erroneous comment
maint: Remove erroneous comment

I added this comment with an incorrect understanding of how
JSAutoSaveExceptionState works. It can't be used for this purpose, since
it doesn't save and restore the state of "no exception".

https://bugzilla.gnome.org/show_bug.cgi?id=751252

endlessm/gjs,endlessm/gjs,endlessm/gjs,endlessm/gjs,endlessm/gjs