DevTools: Send async stack trace with Network.Initiator.

Source/devtools/front_end/networkLogView.css

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 241 matching lines @@
 
 .network-log-grid.data-grid.small .image-network-icon-preview {
     top: 2px;
     bottom: 1px;
     left: 3px;
     right: 3px;
     max-width: 8px;
     max-height: 11px;
 }
 
+.network-async-trace-description {
+    padding: 3px 0 1px 0;
+    font-style: italic;
+}
+
 /* Graph styles */
 
 .network-graph-side {
     position: relative;
     height: 36px;
     padding: 0;
     white-space: nowrap;
     margin-top: 1px;
     border-top: 1px solid transparent;
     overflow: hidden;
@@ skipping 325 matching lines @@
 }
 
 #network-container:not(.brief-mode) .data-grid tr.selected {
     background-color: transparent;
     color: #222;
 }
 
 #network-container.brief-mode .data-grid .data-container {
     padding-right: 0;
 }