Clarify retry() when errorFields are not passed (#825)

Author: marcoscaceres

index.html

@@ -3202,16 +3202,24 @@ <h2>
                   </li>
                 </ol>
               </li>
+              <li data-link-for="PaymentValidationErrors">By matching the
+              members of <var>errorFields</var> to input fields in the user
+              agent's UI, indicate to the end-user that something is wrong with
+              the data of the payment response. For example, a user agent might
+              draw the user's attention to the erroneous <var>errorFields</var>
+              in the browser's UI and display the value of each field in a
+              manner that helps the user fix each error. Similarly, if the <a>
+                error</a> member is passed, present the error in the user
+                agent's UI. In the case where the value of a member is the
+                empty string, the user agent MAY substitute a value with a
+                suitable error message.
+              </li>
             </ol>
           </li>
-          <li data-link-for="PaymentValidationErrors">By matching the members
-          of <var>errorFields</var> to input fields in the user agent's UI,
-          indicate to the end-user that something is wrong with the data of the
-          payment response. For example, a user agent might draw the user's
-          attention to the erroneous <var>errorFields</var> in the browser's UI
-          and display the value of each field in a manner that helps the user
-          fix each error. Similarly, if the <a>error</a> member is passed,
-          present the error in the user agent's UI.
+          <li>Otherwise, if <var>errorFields</var> was not passed, signal to
+          the end user to attempt to retry the payment. Re-enable
+          any UI element that affords the end-user the ability to retry
+          accepting the payment request.
           </li>
           <li data-tests=
           "payment-response/rejects_if_not_active-manual.https.html">If