DevTools: migrate navigator icons to UI.Icon

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

 /*
  * Copyright 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.
  */
 
 :host {
     flex: 1 1;
     padding: 2px 0 0 0;
 }
@@ skipping 70 matching lines @@
 }
 
 ol.tree-outline:focus li.selected {
     color: white;
 }
 
 ol.tree-outline:focus li.selected * {
     color: inherit;
 }
 
-.tree-outline li .icons-container {
+.tree-outline li .leading-icons {
+    align-self: center;
+    display: flex;
+    align-items: center;
+}
+
+.tree-outline li .trailing-icons {
     margin-left: 4px;
     align-self: center;
 }
 
 .tree-outline li::before {
     -webkit-user-select: none;
     -webkit-mask-image: url(Images/toolbarButtonGlyphs.png);
     -webkit-mask-size: 352px 168px;
     content: "aa";
     color: transparent;
@@ skipping 38 matching lines @@
     margin-top: 0;
 }
 
 .tree-outline.tree-outline-dense li.parent::before {
     top: 0;
 }
 
 .tree-outline.tree-outline-dense ol {
     padding-left: 10px;
 }