[DevTools] Get rid of floats in treeoutline.

third_party/WebKit/Source/devtools/front_end/network/requestHeadersView.css

 /*
  * Copyright (c) 2014 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 .request-headers-view {
     -webkit-user-select: text;
     overflow: auto;
 }
@@ skipping 14 matching lines @@
     color: #616161;
     margin-top: -1px;
     height: 20px;
     border-top: solid 1px #e0e0e0;
     display: flex;
     align-items: center;
 }
 
 .request-headers-view .outline-disclosure li.parent::before {
     position: static;
-    width: 9px;
+    width: 13px;
     height: 9px;
     -webkit-mask-position: -4px -98px;
     background-image: none;
     opacity: 1;
 }
 
 .request-headers-view .outline-disclosure li.parent.expanded::before {
     -webkit-mask-position: -20px -98px;
 }
 
@@ skipping 62 matching lines @@
     margin-right: 3px;
 }
 
 .request-headers-view .filter-input {
     outline: none !important;
     border: none;
     border-bottom: solid 1px #ccc;
     flex: 0 0 19px;
     padding: 0 4px;
 }