DevTools: make ElementsTreeOutline shadow dom-based.

Source/devtools/front_end/inspectorStyle.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 744 matching lines @@
 }
 
 #drawer-tabbed-pane > .tabbed-pane-header {
     background-color: rgb(236, 236, 236);
 }
 
 #drawer-contents .tabbed-pane-header .tabbed-pane-header-tab {
     cursor: default;
 }
 
-body.platform-mac .monospace,
-body.platform-mac .source-code {
-    font-size: 11px !important;
-    font-family: Menlo, monospace;
-}
-
-body.platform-mac.platform-mac-tiger .monospace,
-body.platform-mac.platform-mac-tiger .source-code {
-    font-size: 10px !important;
-    font-family: Monaco, monospace;
-}
-
-body.platform-windows .monospace,
-body.platform-windows .source-code {
-    font-size: 12px !important;
-    font-family: Consolas, Lucida Console, monospace;
-}
-
-body.platform-linux .monospace,
-body.platform-linux .source-code {
-    font-size: 11px !important;
-    font-family: dejavu sans mono, monospace;
-}
-
 .console-view {
     background-color: white;
     overflow: hidden;
 }
 
 .console-view-wrapper {
     background-color: rgb(236, 236, 236);
 }
 
 .console-status-bar,
@@ skipping 532 matching lines @@
     min-width: 100%;
 }
 
 .outline-disclosure,
 .outline-disclosure ol {
     list-style-type: none;
     -webkit-padding-start: 12px;
     margin: 0;
 }
 
-.source-code {
-    font-family: monospace;
-    font-size: 11px !important;
-    white-space: pre-wrap;
-}
-
 .console-message-text {
     white-space: pre-wrap;
 }
 
 .outline-disclosure li {
     padding: 0 0 0 14px;
     margin-top: 1px;
     margin-left: -2px;
     word-wrap: break-word;
 }
@@ skipping 1476 matching lines @@
 }
 
 .resources-divider-label {
     position: absolute;
     top: 4px;
     right: 3px;
     font-size: 80%;
     white-space: nowrap;
     pointer-events: none;
 }