[Devtools] Accessibility tree: Don't show siblings; always expand any node with children

third_party/WebKit/Source/devtools/front_end/accessibility/accessibilityNode.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.
  */
 
 .sidebar-pane.accessibility-computed {
     background-color: rgba(0, 0, 0, 0.03);
 }
 
@@ skipping 125 matching lines @@
     border: 1px solid #ddd;
     margin-left: 5px;
     margin-bottom: 1px;
 }
 
 li.siblings-expanded button.expand-siblings {
     display: none;
 }
 
 .tree-outline li:hover .inspect-dom-node {
-    display: initial;
+    display: inline-block;
 }
 
 .tree-outline li.no-dom-node:hover .inspect-dom-node,
 .tree-outline li.inspected:hover .inspect-dom-node {
     display: none;
 }
 
 li .inspect-dom-node {
     background-color: #5a5a5a;
     padding: 0;
     margin-left: 5px;
     border: 0;
     display: none;
     position: relative;
     top: 2px;
 }
 
 .tree-outline li.selected:focus .inspect-dom-node {
     background-color: white;
 }
 
 .tree-outline li.hovered:not(.selected) .selection {
     display: block;
     left: 3px;
     right: 3px;
     background-color: rgba(56, 121, 217, 0.1);
     border-radius: 5px;
 }