fixup! Bug 40925: Implemented the Security Level component

Bug 42644: Remove redundant separator CSS rules.

browser/themes/shared/customizableui/panelUI-shared.css

@@ -1308,16 +1308,6 @@ panelview .toolbarbutton-1 {
   }
 }
 
-/* TODO: Check if we can/should merge with the above rule */
-#securityLevel-panel toolbarseparator {
-  appearance: none;
-  min-height: 0;
-  border-top: 1px solid var(--panel-separator-color);
-  border-bottom: none;
-  margin: var(--panel-separator-margin);
-  padding: 0;
-}
-
 .PanelUI-tabitem-container > toolbarbutton[itemtype="tab"],
 #PanelUI-historyItems > toolbarbutton {
   list-style-image: url("chrome://global/skin/icons/defaultFavicon.svg");