Pale Moon 27.1+ support

package.json

@@ -14,6 +14,7 @@
   "engines": {
     "firefox": ">=38.0a1",
     "fennec": ">=38.0a1",
-    "seamonkey": ">=2.0a1 <=2.46"
+    "seamonkey": ">=2.0a1 <=2.46",
+    "{8de7fcbb-c55c-4fbe-bfc5-fc555c87dbc4}": ">=27.1.0b1"
   }
 }