Fix eslint no-useless-escape in es5 files

[MAILPOET-1146]

.eslintrc.es5.json

@@ -20,7 +20,6 @@
     "no-restricted-syntax": 0,
     "no-useless-concat": 0,
     "no-nested-ternary": 0,
-    "no-useless-escape": 0,
     "brace-style": 0,
     "space-infix-ops": 0
   }

assets/js/src/form_editor/form_editor.js

@@ -879,7 +879,7 @@ WysijaForm.Block = window.Class.create({
   createBlockDroppable: function () {
     info('block -> createBlockDroppable');
     this.element.insert({
-      before: '<div class=\"block_placeholder\">' + window.$('block_placeholder').innerHTML + '</div>'
+      before: '<div class="block_placeholder">' + window.$('block_placeholder').innerHTML + '</div>'
     });
     return this.element.previous('.block_placeholder');
   },

assets/js/src/handlebars_helpers.js

@@ -83,7 +83,7 @@ define('handlebars_helpers', ['handlebars'], function (Handlebars) {
     return url + value;
   });
   Handlebars.registerHelper('emailFromMailto', function (value) {
-    var mailtoMatchingRegex = /^mailto\:/i;
+    var mailtoMatchingRegex = /^mailto:/i;
     if (typeof value === 'string' && value.match(mailtoMatchingRegex)) {
       return value.replace(mailtoMatchingRegex, '');
     }

assets/js/src/subscribers/importExport/import.js

@@ -165,7 +165,7 @@ define(
                 email = test[1].trim();
               }
               // test for valid characters using WP's rule (https://core.trac.wordpress.org/browser/tags/4.7.3/src/wp-includes/formatting.php#L2902)
-              if (!/^[a-zA-Z0-9!#$%&\'*+\/=?^_`{|}~\.\-@]+$/.test(email)) {
+              if (!/^[a-zA-Z0-9!#$%&'*+/=?^_`{|}~.-@]+$/.test(email)) {
                 return false;
               }
               return email;