Devtools: Add new row in toolbarButtonGlyphs and layout editor icon

Source/devtools/front_end/elements/elementsTreeOutline.css

 /*
  * Copyright (c) 2014 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 .elements-disclosure {
     width: 100%;
     display: inline-block;
     line-height: normal;
@@ skipping 12 matching lines @@
 
 .elements-disclosure li.parent::before {
     float: left;
     width: 10px;
     box-sizing: border-box;
 }
 
 .elements-disclosure li.parent::before {
     -webkit-user-select: none;
     -webkit-mask-image: url(Images/toolbarButtonGlyphs.png);
-    -webkit-mask-size: 352px 144px;
+    -webkit-mask-size: 352px 168px;
     content: "a";
     color: transparent;
     text-shadow: none;
     margin-right: 1px;
 }
 
 .elements-disclosure li.always-parent::before {
     visibility: hidden;
 }
 
@@ skipping 253 matching lines @@
 }
 
 ol:hover > li > .elements-tree-shortcut-link {
     display: initial;
 }
 
 .elements-tree-shortcut-link {
     color: rgb(87, 87, 87);
     display: none;
 }