This is effectively superseded by the hover / any-hover media queries, which
actually are standard, and is also causing trouble in the wild.
Not even the browser fronted uses it, so we should be able to just remove it
everywhere at once.
Differential Revision: https://phabricator.services.mozilla.com/D49506
This moves most of the code to be Rust, except potentially some evaluator
functions, and allows to unblock the use case from any-hover / any-pointer and
remove nsMediaFeatures.
Differential Revision: https://phabricator.services.mozilla.com/D2976