[DevTools] Migrate StylesSidebarPane to TreeOutlineInShadow.

third_party/WebKit/Source/devtools/BUILD.gn

 # Copyright 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.
 
 import("//build/config/features.gni")
 import("//third_party/WebKit/Source/core/core.gni")
 
 devtools_embedder_scripts = [
   "front_end/devtools.js",
   "front_end/Tests.js",
@@ skipping 391 matching lines @@
 devtools_diff_js_files = [
   "front_end/diff/Diff.js",
   "front_end/diff/diff_match_patch.js",
 ]
 devtools_elements_js_files = [
   "front_end/elements/breadcrumbs.css",
   "front_end/elements/computedStyleSidebarPane.css",
   "front_end/elements/elementsPanel.css",
   "front_end/elements/elementsTreeOutline.css",
   "front_end/elements/platformFontsWidget.css",
+  "front_end/elements/stylesSectionTree.css",
   "front_end/elements/ClassesPaneWidget.js",
   "front_end/elements/ColorSwatchPopoverIcon.js",
   "front_end/elements/ComputedStyleModel.js",
   "front_end/elements/ElementsBreadcrumbs.js",
   "front_end/elements/ElementsPanel.js",
   "front_end/elements/ElementsSidebarPane.js",
   "front_end/elements/ElementsTreeElement.js",
   "front_end/elements/ElementsTreeElementHighlighter.js",
   "front_end/elements/ElementsTreeOutline.js",
   "front_end/elements/ElementStatePaneWidget.js",
@@ skipping 689 matching lines @@
     deps = [
       ":frontend_protocol_sources",
       ":supported_css_properties",
     ]
     sources = generated_scripts
     outputs = [
       "$resources_out_debug_dir/{{source_file_part}}",
     ]
   }
 }