Ensure we support Firefox ESR

Author: philwareham

dist/classic/assets/css/textpattern.css

@@ -55,7 +55,8 @@
   },
   "browserslist": [
     "> 0.5%",
-    "not ie < 11"
+    "Firefox ESR",
+    "IE 11"
   ],
   "scripts": {
     "test": "grunt travis --verbose"