Devtools: Add new row in toolbarButtonGlyphs and layout editor icon

Source/devtools/front_end/elements/computedStyleSidebarPane.css

 /*
  * Copyright (c) 2015 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.
  */
 
 .computed-properties {
     padding: 2px 2px 4px 4px;
     -webkit-user-select: text;
 }
@@ skipping 18 matching lines @@
 .computed-style-property:hover .computed-style-trace-button {
     display: inline-block;
 }
 
 .computed-style-trace-button:hover {
     opacity: 1;
 }
 
 .computed-style-trace-button > .glyph {
     -webkit-mask-image: url(Images/toolbarButtonGlyphs.png);
-    -webkit-mask-size: 352px 144px;
+    -webkit-mask-size: 352px 168px;
     -webkit-mask-position: -224px -24px;
     background-color: rgba(0, 0, 0, 0.75);
     position: absolute;
     top: 0;
     right: 0;
     bottom: 0;
     left: 0;
     margin: 0 -1px;
 }
 
 @media (-webkit-min-device-pixel-ratio: 1.5) {
 .computed-style-trace-button > .glyph {
     -webkit-mask-image: url(Images/toolbarButtonGlyphs_2x.png);
 }
 } /* media */
 
 .computed-style-property {
     position: relative;
     padding-left: 14px;
 }