Bug 1510959 - [RTL] Settings icons on the site identity panel are aligned. r=Ehsan

Icons needed to be moved over by 8px in rtl to match ltr.

Differential Revision: https://phabricator.services.mozilla.com/D13558

--HG--
extra : moz-landing-system : lando

browser/themes/shared/controlcenter/panel.inc.css

@@ -145,7 +145,7 @@
 }
 
 .identity-popup-preferences-button:-moz-locale-dir(rtl) {
-  background-position: center left;
+  background-position: center left 8px;
 }
 
 .identity-popup-preferences-button > .toolbarbutton-text {