DevTools: Disable timeline network pane resizer when network group is collapsed.

third_party/WebKit/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 432 matching lines @@
     overflow: hidden;
     white-space: nowrap;
     text-overflow: ellipsis;
 }
 
 .timeline-flamechart {
     overflow: hidden;
 }
 
 .timeline-flamechart-resizer {
-    height: 7px;
+    height: 8px;
     background-color: #f3f3f3;
-    border-top: #a3a3a3 1px solid;
+    border: 1px #a3a3a3;
+    border-style: solid none;
     display: flex;
     flex-direction: row;
     align-items: flex-end;
     justify-content: center;
 }
 
+.timeline-network-resizer-disabled > .timeline-flamechart-resizer {
+    display: none;
+}
+
 .timeline-flamechart-resizer:after {
     content: "...";
     font-size: 14px;
     margin-bottom: -1px;
 }
 
 .timeline-status-pane.full-widget-dimmed-banner {
     text-align: left !important;
 }
 
@@ skipping 198 matching lines @@
 
 .timeline-landing-warning-close {
     float: right;
     margin-top: -10px;
     margin-right: -13px;
 }
 
 .timeline-landing-warning span[is=ui-icon] {
     margin: -8px;
 }