DevTools: align tabbed pane close tab buttons.

third_party/WebKit/Source/devtools/front_end/ui/tabbedPane.css

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc.  All rights reserved.
  * Copyright (C) 2009 Anthony Ricaud <rik@webkit.org>
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  * 1. Redistributions of source code must retain the above copyright
@@ skipping 108 matching lines @@
     border-top-color: #ccc;
 }
 
 .tabbed-pane-header-tab.dragging {
     position: relative;
     box-shadow: 0 1px 4px 0 rgba(0, 0, 0, 0.37);
     background-color: #e5e5e5;
 }
 
 .tabbed-pane-header-tab .tabbed-pane-close-button {
-    display: inline-block;
-    position: relative;
-    top: 2px;
-    left: 1px;
-    margin-left: 2px;
-    margin-top: -3px;
+    margin: 0 -3px 0 4px;
     visibility: hidden;
 }
 
 .tabbed-pane-header-tab:hover .tabbed-pane-close-button,
 .tabbed-pane-header-tab.selected .tabbed-pane-close-button {
     visibility: visible;
 }
 
 .tabbed-pane-header-tabs-drop-down-container {
     float: left;
@@ skipping 137 matching lines @@
 
 .tabbed-pane-left-toolbar {
     margin-right: -4px;
     flex: none;
 }
 
 .tabbed-pane-right-toolbar {
     margin-left: -4px;
     flex: none;
 }