button-has-type: fix for node 4

Author: ljharb

lib/rules/button-has-type.js

@@ -71,16 +71,17 @@ module.exports = {
       });
     }
 
-    function checkValue(node, value, quote = x => `"${x}"`) {
+    function checkValue(node, value, quoteFn) {
+      const q = quoteFn || (x => `"${x}"`);
       if (!(value in configuration)) {
         context.report({
           node: node,
-          message: `${quote(value)} is an invalid value for button type attribute`
+          message: `${q(value)} is an invalid value for button type attribute`
         });
       } else if (!configuration[value]) {
         context.report({
           node: node,
-          message: `${quote(value)} is a forbidden value for button type attribute`
+          message: `${q(value)} is a forbidden value for button type attribute`
         });
       }
     }