Bug 1059100 - [email] 2.0-specific XOAuth2 mitigation

What about kicking out the system browser? That would possibly save the user some steps in signing in if they have used google for it (I'm assuming it is most likely they are using same account for email), and they could have nice things like a URL bar if they felt inclined to check the location?

If you wanted, you could abstract the window.open popping to a module that just exports a function and when that function is called, it does the window work? `require('gmail_rejects_us')()`.

Both are totally optional feedback though. Since you tested this on device already, I'm fine with this as-is, it is a stop-gap fix anyway.