Leverage the font-display CSS feature

[rejhgadellaa]

Is your feature request related to a problem? Please describe.

Lighthouse has the following to say when I include firebase-ui css in my project:

Leverage the font-display CSS feature to ensure text is user-visible while webfonts are loading.

Describe the solution you'd like

Use Google Fonts' &display={value} parameter in imports.css like so:

@import url(https://fonts.googleapis.com/css?family=Roboto:400,500,700&display=swap);

Describe alternatives you've considered

Host a modified version of the firebase-ui css file on my own server

Additional context

Lighthouse's Learn More has a separate chapter covering Google Fonts:
https://web.dev/font-display/?utm_source=lighthouse&utm_medium=devtools#google-fonts