DevTools: added support for image url & node in tracing-based timeline

LayoutTests/inspector/tracing-test.js

 function initialize_TracingTest()
 {
 
 // FIXME: remove when tracing is out of experimental
 WebInspector.inspectorView.showPanel("timeline");
 InspectorTest.tracingModel = new WebInspector.TracingModel();
 
 InspectorTest.invokeWithTracing = function(categoryFilter, functionName, callback)
 {
     InspectorTest.tracingModel.start(categoryFilter, "", onTracingStarted);
 
     function onTracingStarted(error)
     {
-        InspectorTest.invokePageFunctionAsync(functionName, onPageActionsDone)
+        InspectorTest.invokePageFunctionAsync(functionName, onPageActionsDone);
     }
 
     function onPageActionsDone()
     {
-        InspectorTest.tracingModel.stop(callback);
+        InspectorTest.tracingModel.stop(InspectorTest.safeWrap(callback));
     }
 }
 
 }