[DevTools] Remove SidebarTreeElement from SecurityPanel.

third_party/WebKit/Source/devtools/front_end/security/sidebar.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.
  */
 
 .tree-outline {
     padding: 0;
 }
 
 .tree-outline li {
     display: flex;
     flex-direction: row;
     align-items: center;
+    padding: 2px 5px;
+    overflow: hidden;
+    margin: 2px 0;
+    border-top: 1px solid transparent;
+    white-space: nowrap;
 }
 
 .tree-outline:focus li.selected .lock-icon,
 .tree-outline:focus .security-sidebar-tree-item.selected .icon
 {
     background-color: white;
 }
 
 .tree-outline .security-main-view-sidebar-tree-item {
     border-bottom: 1px solid rgb(230, 230, 230);
     padding: 16px 0;
 }
 
-.tree-outline .security-sidebar-origins {
-    padding: 1px 8px 6px 8px;
+.tree-outline li.security-sidebar-origins {
+    padding: 1px 8px 1px 13px;
     margin-top: 1em;
     margin-bottom: 0.5em;
     color: rgb(90, 90, 90);
+    border-top: none;
+    line-height: 16px;
+    text-shadow: rgba(255, 255, 255, 0.75) 0 1px 0;
 }
 
 .tree-outline ol {
     padding-left: 0;
 }
 
 .tree-outline li::before {
     content: none;
 }
 
 .tree-outline .security-main-view-sidebar-tree-item,
 .tree-outline .security-sidebar-origins,
-.tree-outline .sidebar-tree-section + .children > .sidebar-tree-item {
+.tree-outline li.security-sidebar-origins + .children > li {
     padding-left: 16px;
 }
 
-.tree-outline .sidebar-tree-item .lock-icon,
-.tree-outline .sidebar-tree-item .security-property {
+.tree-outline .lock-icon,
+.tree-outline .security-property {
     margin-right: 4px;
     flex: none;
 }
 
 .security-sidebar-tree-item {
     padding: 2px 0;
 }
 
-.security-sidebar-tree-item .titles {
+.security-sidebar-tree-item .title {
     overflow: hidden;
     margin-right: 5px;
 }
 
-.sidebar-tree-item.security-main-view-reload-message .title {
+.security-main-view-reload-message .tree-element-title {
     color: rgba(0, 0, 0, 0.5);
     padding-left: 8px;
 }