Bug 1505334 - Fix --toolbarbutton-icon-fill-opacity override for the tabs toolbar using the Dark / Light themes on Aero Glass. r=ntim

Differential Revision: https://phabricator.services.mozilla.com/D11160

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

browser/themes/windows/compacttheme.css

@@ -59,9 +59,9 @@
 }
 
 @media (-moz-windows-glass) {
-  /* Set to full fill-opacity to improve visibility of toolbar buttons on aero glass. */
+  /* Use opaque white icons on Aero Glass. */
   #TabsToolbar {
-    --toolbarbutton-icon-fill-opacity: 1;
+    --lwt-toolbarbutton-icon-fill: white;
   }
 
   /* Make the menubar text readable on aero glass (copied from browser-aero.css). */