DevTools: make ElementsTreeOutline shadow dom-based.

Source/devtools/devtools.gypi

 #
 # 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 287 matching lines @@
         ],
         'devtools_standalone_files': [
             'front_end/accelerometer.css',
             'front_end/auditsPanel.css',
             'front_end/breakpointsList.css',
             'front_end/canvasProfiler.css',
             'front_end/cmdevtools.css',
             'front_end/dataGrid.css',
             'front_end/devicesView.css',
             'front_end/documentationView.css',
+            'front_end/elementsTreeOutline.css',
             'front_end/elementsPanel.css',
             'front_end/filter.css',
             'front_end/filteredItemSelectionDialog.css',
             'front_end/flameChart.css',
             'front_end/fontView.css',
             'front_end/heapProfiler.css',
             'front_end/helpScreen.css',
             'front_end/imageView.css',
             'front_end/indexedDBViews.css',
             'front_end/inspectorCommon.css',
@@ skipping 332 matching lines @@
             'front_end/Images/touchCursor.png',
             'front_end/Images/touchCursor_2x.png',
             'front_end/Images/transformControls.png',
             'front_end/Images/transformControls_2x.png',
         ],
         'devtools_extension_api_files': [
             'front_end/extensions/ExtensionAPI.js',
         ],
     },
 }