Fix UI glitches on Performance and Memory panels

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 21 matching lines @@
 }
 
 .timeline-settings-pane {
     flex: none;
     border-bottom: 1px solid #dadada;
 }
 
 #timeline-overview-panel {
     flex: none;
     position: relative;
-    border-bottom: 1px solid rgb(140, 140, 140);
+    border-bottom: 1px solid #bbb;
 }
 
 #timeline-overview-panel .timeline-graph-bar {
     pointer-events: none;
 }
 
 #timeline-overview-grid {
     background-color: rgb(255, 255, 255);
 }
 
@@ skipping 616 matching lines @@
 
 .timeline-landing-warning {
     background-color: #fffde7;
     padding: 10px 14px;
     box-shadow: 1px 1px 3px rgba(0,0,0,0.2);
 }
 
 .timeline-landing-warning span[is=ui-icon] {
     margin: -8px;
 }