DevTools: implement hidpi-friendly success/error/warning balls.

Source/devtools/front_end/AuditResultView.js

 /*
  * Copyright (C) 2009 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 63 matching lines @@
     }
 
     categoryResult.ruleResults.sort(ruleSorter);
 
     for (var i = 0; i < categoryResult.ruleResults.length; ++i) {
         var ruleResult = categoryResult.ruleResults[i];
         var treeElement = this._appendResult(this._treeOutline, ruleResult);
         treeElement.listItemElement.addStyleClass("audit-result");
 
         if (ruleResult.severity) {
-            var severityElement = document.createElement("img");
+            var severityElement = document.createElement("div");
             severityElement.className = "severity-" + ruleResult.severity;
             treeElement.listItemElement.appendChild(severityElement);
         }
     }
     this.expand();
 }
 
 WebInspector.AuditCategoryResultPane.prototype = {
     /**
      * @param {(TreeOutline|TreeElement)} parentTreeElement
@@ skipping 25 matching lines @@
         if (result.expanded) {
             treeElement.listItemElement.removeStyleClass("parent");
             treeElement.listItemElement.addStyleClass("parent-expanded");
             treeElement.expand();
         }
         return treeElement;
     },
 
     __proto__: WebInspector.SidebarPane.prototype
 }