Bug 1442078 - Modify UI tests that were broken by the change to the "show" specs. r=MattN

MozReview-Commit-ID: 3KlcOOgarkW

--HG--
extra : rebase_source : cdd9e13d83f6e2e49c8d6b950045e9bb0f6d45ff

toolkit/components/payments/test/PaymentTestUtils.jsm

@@ -85,7 +85,13 @@ var PaymentTestUtils = {
     createAndShowRequest: ({methodData, details, options}) => {
       const rq = new content.PaymentRequest(methodData, details, options);
       content.rq = rq; // assign it so we can retrieve it later
+
+      const handle = content.QueryInterface(Ci.nsIInterfaceRequestor)
+                            .getInterface(Ci.nsIDOMWindowUtils)
+                            .setHandlingUserInput(true);
       content.showPromise = rq.show();
+
+      handle.destruct();
     },
   },