WOFF2 fonts are not supported in themes.

Using the Clean theme: Apply the patch. Place the file 'https://tracker.moodle.org/secure/attachment/42496/font-awesome-MDL-46728.css' in the 'theme/clean/style' folder. Create a new folder 'theme/clean/fonts' and place the files on it 'https://tracker.moodle.org/secure/attachment/42493/fontawesome-webfont.woff2' 'https://tracker.moodle.org/secure/attachment/42495/fontawesome-webfont.eot' In the 'theme/clean/config.php' file, add "$THEME->sheets[] = 'font-awesome- MDL-46728 ';" after "$THEME->sheets = array('custom');". Using a modern browser that supports the WOFF2 format, 'Chrome Version 40.0.2214.93 m' for example. Purge all caches. In a course (topic course format), create a label and with the editor (ATTO) in 'HTML' mode ('Show more buttons' button -> 'HTML' button), add the markup '<i class="fa fa-train"></i>FontAwesome 4.3.0 test.'. Save and return to the course. Observe that the label has a 'train' icon in front of the words 'FontAwesome 4.3.0 test.'. Press F12 to open the developer web tools and reload the page so that the 'fontawesome-webfont.woff2' file will be reported in the network tab. Confirm that the mime-type is 'fontawesome-webfont.woff2' as shown in the 'Response Headers' of the packet that delivered the file. Please see 'https://tracker.moodle.org/secure/attachment/42497/2015-01-29%2013_06_40-Course_%20Topics_MDL-46728.jpg'. Open up Internet Explorer 11 (11.0.9600.17501 used to test) which does not support WOFF2 files but instead EOT files. Go to the course and label you created and observe that the label has a 'train' icon in front of the words 'FontAwesome 4.3.0 test.'. This demonstrates that EOT files are served as before and the 'if' sequence is unharmed.