This is splitted from bug 1401851, even if we're now storing and using more hi dpi favicons, we are not yet comfortable with jut removing crisp-edges. We need to collect and analyze more data to understand if we're at a point where crisp-edges does more damage than benefit. We could store some telemetry about the percentage of pages in favicons.sqlite that don't have an icon larger than 16px. This together with the existing LINK_ICON_SIZES_ATTR_DIMENSIONS telemetry could help us making a call.

I posted the current patch, just as a placeholder, not intending to land it until we have data and a decision.

(In reply to Justin Dolske [:Dolske] from bug 1401777 comment #31) > That this -moz-crisp-edges gets applied to favicons that are *downscaled* is unintentional. At least for the in-tab favicon, similar to the fix in bug 1401777, it should be relatively straightforward to just pass the width data to set a style / class conditionally doing the crisp or smooth scaling.

we don't always know the facicon size, since the "sizes" attribute is optional and often omitted.