jsdialog: hide unused linkbutton

this is shown after commit cf0a6f4
jsdialog: add "linkbutton" as an independent widget

it wasn't there before

Signed-off-by: Szymon Kłos <szymon.klos@collabora.com>
Change-Id: Ibdf8a9eb7f226740c11e8a34c16c7be4177576e6

browser/css/jssidebar.css

@@ -289,7 +289,8 @@ button#button2.ui-pushbutton.jsdialog.sidebar {
 /* not available commands*/
 
 .sidebar #orientationcontrol,
-.sidebar #rotation {
+.sidebar #rotation,
+.sidebar #rotatemenu {
 	visibility: hidden;
 }