This flag has been removed as per https://bugzilla.mozilla.org/show_bug.cgi?format=default&id=1403366, which means that any future Mozilla ebuilds will not be able to use this eclass. We should either remove lines 223 and 224 or create a new eclass which does not set this flag.
We are using other fixes to remove the line in question, creating a new eclass or modifing the existing is a mute point at this point. When the time comes we will create v6 which will be a large rewrite to incorporate many more features that will make updating easier for the mozilla team.
