A lot of the features that the widget generator (at api.html5please.com) suggests are not recognized by Modernizr. Examples:
modernizr has tests for boxsizing, mathml and datalist
they are all in here https://github.com/Modernizr/Modernizr/tree/master/feature-detects
selectors2 on the other hand, nope.
likely just need the right mapping in our json file.