Added showing slow scroll rectangles in Layers panel.

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

 function initialize_LayerTreeTests()
 {
     // FIXME: remove once out of experimental.
     WebInspector.moduleManager.registerModule("layers");
     var extensions = WebInspector.moduleManager.extensions(WebInspector.Panel).forEach(function(extension) {
         if (extension.module().name() === "layers")
             WebInspector.inspectorView.addPanel(new WebInspector.ModuleManagerExtensionPanelDescriptor(extension));
     });
     InspectorTest._layerTreeModel = WebInspector.panel("layers")._model;
 
@@ skipping 83 matching lines @@
     InspectorTest.requestLayers = function(callback)
     {
         InspectorTest._layerTreeModel.addEventListener(WebInspector.LayerTreeModel.Events.LayerTreeChanged, onLayerTreeChanged);
         InspectorTest._layerTreeModel.enable();
         function onLayerTreeChanged()
         {
             InspectorTest._layerTreeModel.removeEventListener(WebInspector.LayerTreeModel.Events.LayerTreeChanged, onLayerTreeChanged);
             callback();
         }
     }
+
+    InspectorTest.dumpViewScrollRect = function(element)
+    {
+        // InspectorTest.addResult("scrollRect: " + JSON.stringify(element.__scrollRect));

[caseq, 2014/02/24 14:38:56]

please remove

[malch, 2014/02/25 10:36:40]

Done.

+        InspectorTest.addObject(element.__scrollRect, {layerId: "skip"}, "", "scrollRect: ");
+    }
+
+    InspectorTest.dumpViewScrollRects = function()
+    {
+        InspectorTest.addResult("View elements dump");
+        var root = WebInspector.panel("layers")._layers3DView._rotatingContainerElement;
+        var scrollRectElements = root.querySelectorAll('.scroll-rect');
+        for (var i = 0, element; element = scrollRectElements[i]; ++i) {

[caseq, 2014/02/24 14:38:56]

scrollRectElements.forEach()?

[malch, 2014/02/25 10:36:40]

https://coderwall.com/p/jcmzxw

+            InspectorTest.dumpViewScrollRect(element);
+        }
+    }
+
+    InspectorTest.dumpModelScrollRects = function()
+    {
+        InspectorTest.addResult("Model elements dump");
+        // InspectorTest.addResult("scrollRectsByLayerId: " + JSON.stringify(InspectorTest._layerTreeModel._scrollRectsByLayerId));

[caseq, 2014/02/24 14:38:56]

Please remove.

[malch, 2014/02/25 10:36:40]

Done.

+        InspectorTest.addObject(InspectorTest._layerTreeModel._scrollRectsByLayerId, {layerId: "skip"}, "", "scrollRectsByLayerId: ");
+    }
 }