DevTools: make ElementsTreeOutline shadow dom-based.

LayoutTests/inspector/audits/audits-test.js

 function initialize_AuditTests()
 {
 
 InspectorTest.preloadPanel("audits");
 
 InspectorTest.collectAuditResults = function()
 {
     WebInspector.panels.audits.showResults(WebInspector.panels.audits.auditResultsTreeElement.children[0].results);
     var liElements = WebInspector.panels.audits.visibleView.element.getElementsByTagName("li");
     for (var j = 0; j < liElements.length; ++j) {
         if (liElements[j].treeElement)
             liElements[j].treeElement.expand();
     }
     InspectorTest.collectTextContent(WebInspector.panels.audits.visibleView.element, "");
 }
 
 InspectorTest.launchAllAudits = function(shouldReload, callback)
 {
     InspectorTest.addSniffer(WebInspector.AuditController.prototype, "_auditFinishedCallback", callback);
     var launcherView = WebInspector.panels.audits._launcherView;
     launcherView._selectAllClicked(true);
     launcherView._auditPresentStateElement.checked = !shouldReload;
     launcherView._launchButtonClicked();
 }
 
 InspectorTest.collectTextContent = function(element, indent)
 {
     var nodeOutput = "";
-    var child = element.firstChild;
+    var child = element.shadowRoot || element.firstChild;
 
+    var nonTextTags = { "STYLE": 1, "SCRIPT": 1 };
     while (child) {
         if (child.nodeType === Node.TEXT_NODE) {
-            nodeOutput += child.nodeValue.replace("\u200B", "");
-        } else if (child.nodeType === Node.ELEMENT_NODE) {
+            if (!nonTextTags[child.parentElement.nodeName])
+                nodeOutput += child.nodeValue.replace("\u200B", "");
+        } else if (child.nodeType === Node.ELEMENT_NODE || child.nodeType === Node.DOCUMENT_FRAGMENT_NODE) {
             if (nodeOutput !== "") {
                 InspectorTest.addResult(indent + nodeOutput);
                 nodeOutput = "";
             }
             if (!child.firstChild && child.className.indexOf("severity") == 0)
                 nodeOutput = "[" + child.className + "] ";
             else
                 InspectorTest.collectTextContent(child, indent + " ");
         }
         child = child.nextSibling;
     }
     if (nodeOutput !== "")
         InspectorTest.addResult(indent + nodeOutput);
 }
 
 }