Previously I was using jQuery 1.7.1 in my code. I was getting the above error. Then I used the jQuery 1.11.1 straight from the google repository
I get this error with PHPStorm debugging with Firefox 2.8 when using jQuery, currently jquery-2.0.2.min. On examining the file, it contains the following statement:
this.isDefaultPrevented=e.defaultPrevented||e.getPreventDefault&&e.getPreventDefault()?U:Y
if you change this to:
this.isDefaultPrevented=e.defaultPrevented?U:Y
the warning stops.