[DevTools] Get rid of floats in treeoutline.

third_party/WebKit/Source/devtools/front_end/elements/elementsTreeOutline.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.
  */
 
 .elements-disclosure {
     width: 100%;
     display: inline-block;
     line-height: normal;
 }
 
 .elements-disclosure li {
     /** Keep margin-left & padding-left in sync with ElementsTreeElements.updateDecorators **/
     padding: 0 0 0 14px;
     margin-top: 1px;
     margin-left: -2px;
     word-wrap: break-word;
     position: relative;
 }
 
 .elements-disclosure li.parent {
     /** Keep it in sync with ElementsTreeElements.updateDecorators **/
     margin-left: -13px;
 }
 
 .elements-disclosure li.parent::before {
-    float: left;
-    width: 10px;
     box-sizing: border-box;
 }
 
 .elements-disclosure li.parent::before {
     -webkit-user-select: none;
     -webkit-mask-image: url(Images/toolbarButtonGlyphs.png);
     -webkit-mask-size: 352px 168px;
-    content: "a";
+    content: "aa";
     color: transparent;
     text-shadow: none;
-    margin-right: 1px;
+    margin-right: -3px;
 }
 
 .elements-disclosure li.always-parent::before {
     visibility: hidden;
 }
 
 @media (-webkit-min-device-pixel-ratio: 1.5) {
 .elements-disclosure li.parent::before {
     -webkit-mask-image: url(Images/toolbarButtonGlyphs_2x.png);
 }
@@ skipping 267 matching lines @@
 ol:focus li.selected .webkit-html-resource-link {
     color: white;
 }
 
 ol:focus li.selected .webkit-html-attribute-name {
     color: #ccc;
 }
 
 .elements-disclosure .gutter-container {
     position: absolute;
+    top: 0;
 }
 
 .elements-disclosure li.selected .gutter-container:not(.has-decorations) {
     left: 0px;
     width: 16.25px;
     height: 18px;
     transform: rotate(-90deg) translateX(-13px) scale(0.8);
     transform-origin: 0% 0%;
     -webkit-mask-image: url(Images/toolbarButtonGlyphs.png);
     -webkit-mask-position: -201px -27px;
     -webkit-mask-size: 352px 168px;
     background-color: white;
     cursor: pointer;
 }
 
 @media (-webkit-min-device-pixel-ratio: 1.5) {
 .elements-disclosure li.selected .gutter-container:not(.has-decorations) {
     -webkit-mask-image: url(Images/toolbarButtonGlyphs_2x.png);
 }
 } /* media */