Issue #3368560 by Harshita mehna: Replace t() calls in classes

src/Form/W3cValidatorSettingsForm.php

@@ -78,8 +78,8 @@ class W3cValidatorSettingsForm extends ConfigFormBase {
 
     $form['validator_url'] = [
       '#type' => 'url',
-      '#title' => t('W3C Validator API endpoint URI'),
-      '#description' => t('URL of the validator script where API call will be targeted.') . '<br/>' .
+      '#title' => $this->t('W3C Validator API endpoint URI'),
+      '#description' => $this->t('URL of the validator script where API call will be targeted.') . '<br/>' .
       $this->t('You can use the official service at @w3cvalidator althought its not recommended.', [
         '@w3cvalidator' => Link::fromTextAndUrl('http://validator.w3.org/check', Url::fromUri('http://validator.w3.org/check'))->toString()
       ]) . '<br/>' .