Bug 1165360 - Force 1x icon for back button and forward button icons in Dev Edition theme;r=MattN

browser/themes/windows/devedition.css

@@ -26,6 +26,20 @@
   box-shadow: none !important;
 }
 
+
+/* Force 1x image for back/forward button for now, otherwise it breaks the
+   layout - Bug 1165360. */
+@media (min-resolution: 1.1dppx) {
+  #back-button,
+  #forward-button {
+    list-style-image: url("chrome://browser/skin/Toolbar.png");
+  }
+  /* The back button region is already set in devedition.inc.css */
+  #forward-button {
+    -moz-image-region: rect(0px, 72px, 18px, 54px);
+  }
+}
+
 #forward-button > .toolbarbutton-icon {
   -moz-border-start: none !important;
 }