Should use jQuery to check classes

[kayue]

in defualt_theme/_inc/global.js , line 315

if ( 'activity-comments' !== form_parent.attr('class') ) {

should be written as

if ( !form_parent.hasClass('activity-comments') ) {

The reason for this is to avoid javascript from malfunctioning after people like me add an additional class.

[djpaul]

(In [3812]) Improve javascript class checks. Fixes #3013