These classes are used to position thumbnails left, right or center respectively but these class names make no sense on mobile and are not helpful to our skin system in general - a thumbnail should always be centered on a 320px screen, and a floatleft class may look better floated right on a theoretical skin with text aligned right.
Let's replace these class names with more semantic ones or drop their usage altogether.
It's not clear from the stylesheet how the magnify class relates to thumbnails. It should be rewritten in terms of the parent thumbnail class and we should consider moving it to the parser if it is not being copied across to Parsoid.
# Acceptance criteria
[] https://gerrit.wikimedia.org/r/c/mediawiki/core/+/647333 merged
[] The `floatleft`, `floatright`, `tright` and `tleft` are replaced with more meaningful classes
[] The `magnify` class is more tightly coupled to the elements that can use it by using a meaningful selector e.g. thumb__magnify instead of .magnify