[Devtools] Fix hover issue with darktheme in network

third_party/WebKit/Source/devtools/front_end/network/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 65 matching lines @@
     display: none;
 }
 
 .network-log-grid.data-grid.small td {
     height: 21px;
 }
 
 .network-waterfall-header, .network-log-grid.data-grid th {
     border-bottom: 1px solid rgb(205, 205, 205);
     border-left: 1px solid rgb(205, 205, 205);
+}
+
+.network-log-grid.data-grid th {
     background: white;
 }
 
 .network-waterfall-header, .network-log-grid.data-grid .header-container {
     height: 31px;
 }
 
 .network-log-grid.data-grid .data-container {
     top: 31px;
 }
@@ skipping 246 matching lines @@
     text-align: center;
     line-height: 28px;
 }
 
 .network-waterfall-header {
     position: absolute;
     border-left: 0px;
     width: 100%;
     display: table;
     z-index: 200;
-    background-color: transparent;
 }
 
 .network-waterfall-header:hover {
     background-color: hsla(0, 0%, 10%, 0.1);
 }
 
 .network-waterfall-header div {
     display: table-cell;
     line-height: 14px;
     margin: auto 0px;
     vertical-align: middle;
     text-align: left;
     font-weight: normal;
     padding: 0px 4px;
     font-size: 11px;
 }
 
-.network-waterfall-header:hover .sort-order-icon-container {
-    background-color: hsl(0, 0%, 90%);
-}
-
 .network-waterfall-header .sort-order-icon-container {
     position: absolute;
     top: 1px;
     right: 0;
     bottom: 1px;
     display: flex;
     align-items: center;
     padding-left: 0px;
-    background-color: white;
 }
 
 .network-waterfall-header .sort-order-icon {
     margin-right: 4px;
     background-image: url(Images/toolbarButtonGlyphs.png);
     background-size: 352px 168px;
     opacity: 0.5;
     width: 8px;
     height: 7px;
     display: none;
 }
 
 .network-waterfall-header .sort-ascending.sort-order-icon {
     display: block;
     background-position: -4px -111px;
 }
 
 .network-waterfall-header .sort-descending.sort-order-icon {
     display: block;
     background-position: -20px -99px;
 }