Angular allows for `<ng-content>` elements to include a selector which
filters which content-projected entries are inserted into the container
depending on whether or not the selector is matched.
With Ivy this feature has not fully worked due to the massive changes
that took place inside of Ivy's styling algorithm code (which is
responsible for assigning classes and styles to an element). This
fix ensures that content-projection can correctly identify which slot
an element should be placed into when class-based selectors are used.
PR Close#27849
e62eeed7d4