Bug 864608 - Update tab drag dropmarker position for Australis. ui-r=shorlander r=fryn

--HG--
extra : rebase_source : 5e6083347b86dc7e6382658e7f9e28852e3c99c4

browser/themes/linux/browser.css

@@ -1651,7 +1651,8 @@ richlistitem[type~="action"][actiontype="switchtab"] > .ac-url-box > .ac-action-
 /* Tab drag and drop */
 .tab-drop-indicator {
   list-style-image: url(chrome://browser/skin/tabbrowser/tabDragIndicator.png);
-  margin-bottom: -11px;
+  margin-bottom: -9px;
+  z-index: 3;
 }
 
 /* In-tab close button */

browser/themes/osx/browser.css

@@ -2297,7 +2297,8 @@ toolbarbutton.chevron > .toolbarbutton-menu-dropmarker {
 
 .tab-drop-indicator {
   list-style-image: url(chrome://browser/skin/tabbrowser/tabDragIndicator.png);
-  margin-bottom: -8px;
+  margin-top: -2px;
+  z-index: 3;
 }
 
 @media (min-resolution: 2dppx) {

browser/themes/windows/browser.css

@@ -1604,7 +1604,8 @@ richlistitem[type~="action"][actiontype="switchtab"] > .ac-url-box > .ac-action-
 /* Tab DnD indicator */
 .tab-drop-indicator {
   list-style-image: url(chrome://browser/skin/tabbrowser/tabDragIndicator.png);
-  margin-bottom: -11px;
+  margin-bottom: -9px;
+  z-index: 3;
 }
 
 /* Tab close button */