Repro steps:
* Create a Phabricator instance where `auth.email-domains` is non-empty and Google SSO is the only authentication provider
* Sign out of all Google accounts
* Sign into a Google account from a domain not listed in `auth.email-domains`
* Try to log into Phabricator
Actual:
I see a Phabricator error page:
```
Registration Failed
The account you are attempting to register with has an invalid email address ([address]). This Phabricator install only allows registration with specific email addresses:
Email address must be [domain]
```
Expected (what other sites that use Google SSO with a domain restriction seem to do, in my experience):
* If you're signed into multiple accounts, and exactly one matches the domain restriction, Google SSO will automatically use that account without prompting you to select one
* If you're signed into one or more accounts, but none of them match the domain restriction, then Google will show this page:
{F685376}
Whose URL is `https://accounts.google.com/AccountChooser?hd=[domain]&continue=[...]<mpl=popup&sarp=1`. This page has a convenient "Add account" button that lets me easily sign in with the appropriate account, rather than Phabricator which seems to automatically select the sole logged-in account and just fail immediately.