Readd css focus override

[epelc]

Hello I noticed the following in the changelog for 0.9.0-rc1 and I was wondering why.

CSS Focus outlines not prevented by default

The css focus outlines tend to be very ugly and go against all other material styles. They also tend to make apps generally look outdated and old. I tried looking for an issue for this but found nothing and I was wondering if there was some reason I missed that someone might want this.

[ThomasBurleson]

@marcysutton - care to provide thoughts here?

[marcysutton]

As a framework, removing global focus styles is a bad idea because it impacts anyone who includes the stylesheet. For Angular Material components, we replace the default focus style with an alternative, spec-compliant focus style. It's really easy to remove global focus style if developers so choose, and they might. But we are being more selective with how we override it.