Can't create account when email contains multiple dots

I haven't confirmed this but a user reported it in 3111332-zen.

They have an email containing multiple dots, which looks like `this.is.an.example@gmail.com` . They were able to create an account on the web but not on Android.

FWIW web now uses the HTML5 validation API instead of a custom regex. The regex it uses is here: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/email#Validation

Start by reproducing account creation on Android with an address such as this.is.an.example@gmail.com, then locate the Android email validation path and compare it with the web HTML5 validation API. Use the linked MDN email-validation reference to check the expected behavior; done means confirming the case and making Android accept valid addresses with multiple dots.

Written by the indexing model from the issue text.