Revert "Issue #2389495 by JonMcl: Suport custom testStrings for icon fonts. Now needs documentation."
Wrongly attributed.
This reverts commit ece555ce.

Instead of storing font information in cache, store it as a variable as it is less likely to change very often. Going forward, fontinfo files (including any changes to fontinfo files) get registered by going to the webfont loader admin page and saving). Better performance in the long run.

Remove the font-loading class if it still exists after 3 seconds. This makes sure the font is not stuck in loading hell and so that the site will actually show up.