Devtools: Add new row in toolbarButtonGlyphs and layout editor icon

Source/devtools/front_end/ui/splitWidget.css

 /*
  * 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
  * notice, this list of conditions and the following disclaimer.
  *
@@ skipping 82 matching lines @@
 }
 
 .shadow-split-widget.hbox.shadow-split-widget-first-is-sidebar > .shadow-split-widget-sidebar:not(.maximized) {
     border: 0;
     border-right: 1px solid rgb(64%, 64%, 64%);
 }
 
 .shadow-split-widget button.sidebar-show-hide-button {
     position: absolute;
     -webkit-mask-image: url(Images/toolbarButtonGlyphs.png);
-    -webkit-mask-size: 352px 144px;
+    -webkit-mask-size: 352px 168px;
     height: 16px;
     width: 16px;
     border: none;
     z-index: 20;
     background-color: #5a5a5a;
 }
 
 .shadow-split-widget button.sidebar-show-hide-button:hover {
     background-color: #333;
 }
@@ skipping 66 matching lines @@
 
 .shadow-split-widget button.bottom-sidebar-show-hide-button.toggled-show {
     -webkit-mask-position: -296px -76px; /* <| */
     transform: rotate(90deg);
 }
 
 .shadow-split-widget button.bottom-sidebar-show-hide-button.toggled-hide {
     -webkit-mask-position: -264px -76px; /* >| */
     transform: rotate(90deg);
 }