DevTools: [wip] move Elements panel off WebInspector.domModel and single tree outline.

LayoutTests/inspector/elements/edit-dom-test.js

 function initialize_EditDOMTests()
 {
 
 InspectorTest.doAddAttribute = function(testName, dataNodeId, attributeText, next)
 {
     InspectorTest.domActionTestForNodeId(testName, dataNodeId, testBody, next);
 
     function testBody(node, done)
     {
         var editorElement = InspectorTest.editNodePart(node, "webkit-html-attribute");
@@ skipping 41 matching lines @@
     function step2()
     {
         InspectorTest.addResult("==== after ====");
         InspectorTest.dumpElementsTree(testNode);
         next();
     }
 }
 
 InspectorTest.editNodePart = function(node, className)
 {
-    var treeElement = WebInspector.panels.elements.treeOutline.findTreeElement(node);
+    var treeElement = InspectorTest.firstElementsTreeOutline().findTreeElement(node);
     var textElement = treeElement.listItemElement.getElementsByClassName(className)[0];
     if (!textElement && treeElement.childrenListElement)
         textElement = treeElement.childrenListElement.getElementsByClassName(className)[0];
     treeElement._startEditingTarget(textElement);
     return textElement;
 }
 
 InspectorTest.editNodePartAndRun = function(node, className, newValue, step2, useSniffer)
 {
     var editorElement = InspectorTest.editNodePart(node, className);
     editorElement.textContent = newValue;
     editorElement.dispatchEvent(InspectorTest.createKeyEvent("Enter"));
     if (useSniffer)
         InspectorTest.addSniffer(WebInspector.ElementsTreeUpdater.prototype, "_updateModifiedNodes", step2);
     else
         InspectorTest.runAfterPendingDispatches(step2);
 }
 
 }