Bug 1366079 - don't show the overflow button in windows where we hide the toolbar, r=bgrins

MozReview-Commit-ID: GWDx5nRD6rI

--HG--
extra : rebase_source : 46e57e7f4753c3db77c5c48beb450df8e5477210

browser/base/content/browser.css

@@ -224,7 +224,7 @@ toolbar[customizing] > .overflow-button {
   display: none;
 }
 
-#nav-bar[nonemptyoverflow] > .overflow-button,
+window:not([chromehidden~="toolbar"]) #nav-bar[nonemptyoverflow] > .overflow-button,
 #nav-bar[customizing][photon-structure] > .overflow-button {
   display: -moz-box;
 }