Bug 1362281 - Fix forward button styling for macOS. r=johannh

MozReview-Commit-ID: V2EMoAsqDt

--HG--
extra : rebase_source : af553c450d7d465a709787a9b18fadbecc383f51
extra : amend_source : baa051b2c3a995ae890a31bbca3002ebdfd2b739

browser/themes/osx/browser.css

@@ -581,6 +581,20 @@ toolbarpaletteitem[place="palette"] > #personal-bookmarks > #bookmarks-toolbar-p
   list-style-image: url("chrome://browser/skin/menu-forward.png") !important;
 }
 
+@media (-moz-mac-yosemite-theme) {
+  #forward-button > .toolbarbutton-icon {
+    border-top: none !important;
+    border-bottom: none !important;
+    box-shadow: none !important;
+    box-shadow: 0 .5px 0 0 rgba(0,0,0,0.2) !important;
+  }
+  #forward-button:-moz-window-inactive > .toolbarbutton-icon {
+    box-shadow: 0 1px 0 0 rgba(0,0,0,0.2) inset,
+                0 -1px 0 0 rgba(0,0,0,0.2) inset !important;
+  }
+}
+
+
 /* ----- FULLSCREEN WINDOW CONTROLS ----- */
 
 #minimize-button,