[abryzak]

And in fact their FAQ for donations doesn't even mention Firefox under their "How will my donation be used?" section:

At Mozilla, our mission is to keep the Internet healthy, open, and accessible for all. The Mozilla Foundation programs are supported by grassroots donations and grants. Our grassroots donations, from supporters like you, are our most flexible source of funding. These funds directly support advocacy campaigns (i.e. asking big tech companies to protect your privacy), research and publications like the *Privacy Not Included buyer's guide and Internet Health Report, and covers a portion of our annual MozFest gathering.