Update fontface.json (#7117)

Safari added support for `@font-face` in October 2007. 
https://webkit.org/blog/124/downloadable-fonts/

Which means Safari 3.1 for Mac had support in March 2008. This PR updates that bit of information.

Author: jensimmons

features-json/fontface.json

@@ -352,7 +352,7 @@
       "129":"y"
     },
     "safari":{
-      "3.1":"n",
+      "3.1":"y",
       "3.2":"y",
       "4":"y",
       "5":"y",