Add deprecation notices

chrome/full_width_urlbar_popup.css

@@ -1,3 +1,5 @@
+/* DEPRECATED - USE urlbar_full_width.css instead */
+
 /* Makes urlbar popup fit to window width, like in Firefox versions < 71 without "Megabar" */
 /* Text won't be aligned to urlbar text though, since that relied on Firefox setting some css variables which are not available anymore */
 #urlbar{

chrome/google_style_urlbar_popup.css

@@ -1,3 +1,5 @@
+/* DEPRECATED AS OF FIREFOX 77 */
+
 /* Makes urlbar popup to appear Like on various Google search services */
 /* Firefox 70+ only */
 /* Popup uses colors from your theme */

chrome/urlbar_and_popup_equal_width.css

@@ -1,3 +1,4 @@
+/* DEPRECATED AS OF FIREFOX 75 */
 /* Constrains urlbar popup to urlbar width */
 /* Firefox 70+ */