Add :enabled to disableSelector

Ensures elements aren’t disabled twice.

Author: Paulo Pereira

src/rails.js

@@ -37,7 +37,7 @@
     formInputClickSelector: 'form input[type=submit], form input[type=image], form button[type=submit], form button:not([type])',
 
     // Form input elements disabled during form submission
-    disableSelector: 'input[data-disable-with], button[data-disable-with], textarea[data-disable-with]',
+    disableSelector: 'input[data-disable-with]:enabled, button[data-disable-with]:enabled, textarea[data-disable-with]:enabled',
 
     // Form input elements re-enabled after form submission
     enableSelector: 'input[data-disable-with]:disabled, button[data-disable-with]:disabled, textarea[data-disable-with]:disabled',