Test suite: disable test that is broken due to a Tor Browser bug.

Refs: #15336

features/torified_browsing.feature

@@ -139,7 +139,8 @@ Feature: Browsing the web using the Tor Browser
     And I can save the current page as "index.html" to the persistent Tor Browser directory
     When I open the address "file:///home/amnesia/Persistent/Tor Browser/index.html" in the Tor Browser
     Then I see "TorBrowserSavedStartupPage.png" after at most 10 seconds
-    And I can print the current page as "output.pdf" to the persistent Tor Browser directory
+    # XXX: re-enable once #15336 is fixed
+    # And I can print the current page as "output.pdf" to the persistent Tor Browser directory
 
   #11585
   @fragile