[DevTools] Migrate StylesSidebarPane to TreeOutlineInShadow.

third_party/WebKit/LayoutTests/http/tests/inspector/elements-test.js

 var initialize_ElementTest = function() {
 
 InspectorTest.preloadPanel("elements");
 
 InspectorTest.inlineStyleSection = function()
 {
     return WebInspector.panels.elements._stylesWidget._sectionBlocks[0].sections[0];
 }
 
 InspectorTest.computedStyleWidget = function()
@@ skipping 356 matching lines @@
             }
             printStyleSection(section, omitLonghands, includeSelectorGroupMarks);
         }
     }
 }
 
 function printStyleSection(section, omitLonghands, includeSelectorGroupMarks)
 {
     if (!section)
         return;
-    InspectorTest.addResult("[expanded] " + (section.element.classList.contains("no-affect") ? "[no-affect] " : ""));
+    InspectorTest.addResult("[expanded] " + (section.propertiesTreeOutline.element.classList.contains("no-affect") ? "[no-affect] " : ""));
 
     var medias = section._titleElement.querySelectorAll(".media-list .media");
     for (var i = 0; i < medias.length; ++i) {
         var media = medias[i];
         InspectorTest.addResult(media.textContent);
     }
     var selector = section._titleElement.querySelector(".selector") || section._titleElement.querySelector(".keyframe-key");
     var selectorText = includeSelectorGroupMarks ? buildMarkedSelectors(selector) : selector.textContent;
     // Dump " {".
     selectorText += selector.nextSibling.textContent;
@@ skipping 589 matching lines @@
 InspectorTest.dumpAnimationTimeline = function(timeline)
 {
     for (var ui of timeline._uiAnimations) {
         InspectorTest.addResult(ui.animation().type());
         InspectorTest.addResult(ui._nameElement.innerHTML);
         InspectorTest.addResult(ui._svg.innerHTML);
     }
 }
 
 };