Check transient activation after sharePromise (#183)

WPT web-share/share-sharePromise-internal-slot.https.html
has multiple navigator.share() calls within a single
onclick handler. This is a good way to test the sharePromise
internal slot, but it was not previously permitted by the spec,
as the first call would consume activation and the later calls
would fail with NotAllowedError instead of InvalidStateError.

Co-authored-by: Eric Willigers <ericwilligers@chromium.org>

index.html

@@ -150,6 +150,9 @@ <h4>
             permission, return [=a promise rejected with=] with a
             {{"NotAllowedError"}} {{DOMException}}.
             </li>
+            <li>If {{[[sharePromise]]}} is not `null`, return <a>a promise
+            rejected with</a> {{InvalidStateError}}.
+            </li>
             <li>Let |window| be [=relevant global object=] of [=this=].
             </li>
             <li>If |window| does not have [=transient activation=], return [=a
@@ -158,9 +161,6 @@ <h4>
             </li>
             <li>[=Consume user activation=] of |window|.
             </li>
-            <li>If {{[[sharePromise]]}} is not `null`, return <a>a promise
-            rejected with</a> {{InvalidStateError}}.
-            </li>
             <li>If none of |data|'s members {{ShareData/title}},
             {{ShareData/text}}, or {{ShareData/url}} or {{ShareData/file}} are
             present, return <a>a promise rejected with</a> a {{TypeError}}.