DevTools: Use JS symbols instead of strings for eligible events.

third_party/WebKit/LayoutTests/inspector/elements/edit/set-outer-html-test.js

 var initialize_SetOuterHTMLTest = function() {
 
 InspectorTest.events = [];
 InspectorTest.containerId;
 
 InspectorTest.setUpTestSuite = function(next)
 {
     InspectorTest.expandElementsTree(step1);
 
     function step1()
@@ skipping 23 matching lines @@
 InspectorTest.recordEvent = function(eventName, event)
 {
     if (!event.data || event.type === WebInspector.DOMModel.Events.MarkersChanged || event.type === WebInspector.DOMModel.Events.DOMMutated)
         return;
     var node = event.data.node || event.data;
     var parent = event.data.parent;
     for (var currentNode = parent || node; currentNode; currentNode = currentNode.parentNode) {
         if (currentNode.getAttribute("id") === "output")
             return;
     }
-    InspectorTest.events.push("Event " + eventName + ": " + node.nodeName());
+    InspectorTest.events.push("Event " + eventName.toString() + ": " + node.nodeName());
 }
 
 InspectorTest.patchOuterHTML = function(pattern, replacement, next)
 {
     InspectorTest.addResult("Replacing '" + pattern + "' with '" + replacement + "'\n");
     InspectorTest.setOuterHTML(InspectorTest.containerText.replace(pattern, replacement), next);
 }
 
 InspectorTest.patchOuterHTMLUseUndo = function(pattern, replacement, next)
 {
@@ skipping 47 matching lines @@
         InspectorTest.addResult("==========8<==========");
         InspectorTest.addResult(text);
         InspectorTest.addResult("==========>8==========");
         if (last)
             InspectorTest.addResult("\n\n\n");
         next();
     }
 }
 
 };