Merge pull request #7463 from Snuffleupagus/fix-bug-1268749-fallout

Add back moz-specific fullscreen support code for ´MOZCENTRAL` builds (bug 1268749, PR 7273 follow-up)

web/app.js

@@ -416,7 +416,8 @@ var PDFViewerApplication = {
 
   get supportsFullscreen() {
 //#if MOZCENTRAL
-//  var support = document.fullscreenEnabled === true;
+//  var support = document.fullscreenEnabled === true ||
+//                document.mozFullScreenEnabled === true;
 //#else
     var doc = document.documentElement;
     var support = !!(doc.requestFullscreen || doc.mozRequestFullScreen ||