Consume user activation (#916)

Author: marcoscaceres

index.html

@@ -157,6 +157,9 @@ 
           li>
           <li>Deprecated `allowpaymentrequest` attribute.
           li>
+          <li>Calling {{PaymentRequest/show()}} now consumes the user
+          activation.
+          li>
         ul>
       section>
     section>
@@ -990,16 +993,19 @@ 
           follows:
         p>
         <ol class="algorithm">
+          <li>Let |request:PaymentRequest| be [=this=].
+          li>
           <li data-tests=
           "payment-request-show-method.https.html, show-method-postmessage-manual.https.html">
-          If the [=relevant global object=] of [=this=] does not have
+          If the [=relevant global object=] of [=request=] does not have
           [=transient activation=], return [=a promise rejected with=] with a
-          {{"SecurityError"}} {{DOMException}}.
+          {{"NotAllowedError"}} {{DOMException}}.
           li>
-          <li>Let |request:PaymentRequest| be [=this=].
+          <li data-tests="show-consume-activation.https.html">[=Consume user
+          activation=] of the [=relevant global object=].
           li>
-          <li>Let |document| be |request|'s [=relevant global object=]'s [=
-          associated `Document`=].
+          <li>Let |document| be |request|'s [=relevant global object=]'s
+          [=associated `Document`=].
           li>
           <li data-tests="rejects_if_not_active.https.html">If |document| is
           not [=Document/fully active=], then return <a>a promise rejected