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

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

 var initialize_ElementTest = function() {
 
 InspectorTest.findNode = function(matchFunction, callback)
 {
     callback = InspectorTest.safeWrap(callback);
     var result = null;
     var pendingRequests = 0;
     function processChildren(node)
     {
         try {
@@ skipping 152 matching lines @@
 
     function stylesCallback(targetNode)
     {
         InspectorTest.addSniffer(WebInspector.ComputedStyleSidebarPane.prototype, "onContentReady", callback);
         WebInspector.panels.elements.sidebarPanes.computedStyle.expand();
     }
 
     InspectorTest.selectNodeAndWaitForStyles(idValue, stylesCallback);
 }
 
+InspectorTest.firstElementsTreeOutline = function()
+{
+    return WebInspector.panels.elements._treeOutlines[0];
+}
+
 InspectorTest.dumpSelectedElementStyles = function(excludeComputed, excludeMatched, omitLonghands, includeSelectorGroupMarks)
 {
     function extractText(element)
     {
         var text = element.textContent;
         if (text)
             return text;
         var anchor = element.querySelector("[data-uncopyable]");
         if (!anchor)
             return "";
@@ skipping 298 matching lines @@
         var children = treeItem.children;
         var newPrefix = treeItem === treeItem.treeOutline ? "" : prefix + "    ";
         for (var i = 0; depth && children && i < children.length; ++i) {
             if (!children[i]._elementCloseTag)
                 print(children[i], newPrefix, depth - 1);
             else
                 print(children[i], prefix, depth);
         }
     }
 
-    var treeOutline = WebInspector.panels.elements.treeOutline;
+    var treeOutline = InspectorTest.firstElementsTreeOutline();
     treeOutline._updateModifiedNodes();
     print(rootNode ? treeOutline.findTreeElement(rootNode) : treeOutline, "", depth || 10000);
 };
 
 InspectorTest.expandElementsTree = function(callback)
 {
     callback = InspectorTest.safeWrap(callback);
 
     function expand(treeItem)
     {
         var children = treeItem.children;
         for (var i = 0; children && i < children.length; ++i) {
             children[i].expand();
             expand(children[i]);
         }
     }
 
     function onAllNodesAvailable()
     {
-        WebInspector.panels.elements.treeOutline._updateModifiedNodes();
-        expand(WebInspector.panels.elements.treeOutline);
+        InspectorTest.firstElementsTreeOutline()._updateModifiedNodes();
+        expand(InspectorTest.firstElementsTreeOutline());
         callback();
     }
     WebInspector.inspectorView.showPanel("elements");
     InspectorTest.findNode(function() { return false; }, onAllNodesAvailable);
 };
 
 InspectorTest.dumpDOMAgentTree = function(node)
 {
     if (!WebInspector.domModel._document)
         return;
@@ skipping 209 matching lines @@
 {
     var rectNames = ["margin", "border", "padding", "content"];
     var rects = window.internals.inspectorHighlightRects(document);
     for (var i = 0; i < rects.length; i++)
     {
         var rectName = (i < rectNames.length ? rectNames[i] : "untitled");
         var rect = rects.item(i);
         output(rectName + " rect is " + rect.width + " x " + rect.height + " at (" + rect.left + ", " + rect.top + ")");
     }
 }