Help: test-contains-selector

The "test-contains-selector" command:

Usage: fossil test-contains-selector FILENAME SELECTOR

Determine if the CSS stylesheet FILENAME contains SELECTOR.

Note that as of 2020-05-28, the default rules are always emitted,
so the containsSelector() logic is no longer applied when emitting
style.css. It is unclear whether this test command is now obsolete
or whether it may still serve a purpose.