[invalidations] Convert invalidations to use TreeOutline

Source/devtools/front_end/timeline/timelinePanel.css

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc.  All rights reserved.
  * Copyright (C) 2009 Anthony Ricaud <rik@webkit.org>
  *
  * 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 850 matching lines @@
 
 .timeline-gap {
     flex: none;
 }
 
 .invalidations-group {
     margin-top: 4px;
     line-height: normal;
 }
 
-.invalidations-group > .header {
-    padding-left: 0;
+.invalidations-header > .timeline-expandable-arrow {
+    display: inline-block;
+    margin-right: 5px;
+    top: 0;
 }
 
 .invalidations-group > .content {
     margin-left: 25px;
 }
 
 .invalidations-group > .content > .node-list {
     border-left: 1px solid #e1e1e1;
 }
 
 .timeline.panel .status-bar::shadow .timeline-status-bar-group-label {
     margin-left: 12px;
     margin-right: 6px;
     color: #888;
 }