Add ability to load a font without applying CSS rules

When attempting to custom-design a site on .com, I always find myself fighting with the CSS output by custom fonts quite a bit, meaning a hairy mess of lengthy rules and `!important` flags everywhere. Getting things to look the way I want takes way longer than it should, because I need to go through and find all the rules in order to overwrite them.

Would there be a way to load the typeface, but disable the custom CSS output? That way, we could access and use the font files (`@imports` are blocked in custom CSS, otherwise I'd try that route) while using my own (sensible) rules. An a8c-only checkbox option, maybe?

See here also: https://to51.wordpress.com/2016/09/09/heather-meeker-launched/

No files or tests are named. Start by locating the code that loads custom fonts and emits their CSS, then determine where an opt-out setting could be represented; done means the font files load without the plugin's custom CSS rules being applied.

Written by the indexing model from the issue text.