Simplify _CssStateMixin.

1. Remove detection for hover and active (just use :hover, :active or mobile equiv).
2. Remove multiply.   For CSS rules matching multiple conditions, use something
    like .duiToggleButtonChecked.duiToggleButtonDisabled rather than
    .duiToggleButtonCheckedDisabled.
3. Remove CSS setting for sub nodes; it was mainly hover and active anyway.
use :hover and :active in CSS rather than selectors from old _CssStateMixin