I think we're just making a big deal out of this. As someone pointed out, they're likely using technologies not implemented in other browsers yet. Has the OP tried using play store on Aurora? In any case, I feel Google has the ethical and moral right to use whatever they see fit for their own web applications. And let this be said people, this isn't something new. Not even from Google. Inbox doesn't work on non-chrom…
Are you sure? I can login to iCloud just fine on Firefox (35.0.1) and Canary.