Add missing obtain permission in NDEFWriter.push algorithm (#528)

Author: beaufortfrancois

index.html

@@ -2412,6 +2412,11 @@ <h3><dfn>Writing or pushing content</dfn></h3>
                   requested operation.
                 </p>
               </li>
+              <li>
+                If the <a>obtain permission</a> steps return `false`, then
+                reject |p| with a {{"NotAllowedError"}} {{DOMException}} and
+                abort these steps.
+              </li>
               <li>
                 Let |output| be the notation for the <a>NDEF message</a>
                 to be created by UA, as the result of passing