Bug 1273344 - Fix --tab-background-color in a place where it got missed by bug 1205330. r=bgrins

--HG--
extra : amend_source : 5e28d80ee250139f575a200d7a3349eee3b7e63a
extra : histedit_source : dddafd40e6f4f6177405d49741799fd1c6af35b3

browser/themes/shared/devedition.inc.css

@@ -29,7 +29,7 @@
 
   /* Tabs */
   --tabs-toolbar-color: #F5F7FA;
-  --tab-background-color: #1C2126;
+  --tab-background-color: #272b35;
   --tab-hover-background-color: #07090a;
   --tab-selection-color: #f5f7fa;
   --tab-selection-background-color: #5675B9;