DevTools: Freshen up popover styles.

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 536 matching lines @@
             'front_end/Images/statusbarButtonGlyphs_2x.png',
             'front_end/Images/statusbarResizerHorizontal.png',
             'front_end/Images/statusbarResizerVertical.png',
             'front_end/Images/thumbActiveHoriz.png',
             'front_end/Images/thumbActiveVert.png',
             'front_end/Images/thumbHoriz.png',
             'front_end/Images/thumbVert.png',
             'front_end/Images/thumbHoverHoriz.png',
             'front_end/Images/thumbHoverVert.png',
             'front_end/Images/toolbarItemSelected.png',
-            'front_end/Images/trackHoriz.png',
-            'front_end/Images/trackVert.png',
         ],
         'devtools_layers_js_files': [
             'front_end/layers/LayersPanel.js',
             'front_end/layers/LayerTreeOutline.js',
             'front_end/layers/LayerDetailsView.js',
             'front_end/layers/LayerPaintProfilerView.js'
         ],
         'devtools_extension_api_files': [
             'front_end/extensions/ExtensionAPI.js',
         ],
         'devtools_temp_storage_shared_worker_js_files': [
             'front_end/temp_storage_shared_worker/TempStorageSharedWorker.js',
         ],
         'devtools_script_formatter_worker_js_files': [
             'front_end/script_formatter_worker/CSSFormatter.js',
             'front_end/script_formatter_worker/JavaScriptFormatter.js',
             'front_end/script_formatter_worker/ScriptFormatterWorker.js',
             'front_end/common/utilities.js',
         ],
     },
 }