Assert on a null widget Ptr

view/src/nsView.cpp

@@ -175,6 +175,8 @@ nsIView* nsView::GetViewFor(nsIWidget* aWidget)
   nsIView*  view = nsnull;
   void*     clientData;
 
+  NS_PRECONDITION(nsnull != aWidget, "null widget ptr");
+	
   // The widget's client data points back to the owning view
   if (NS_SUCCEEDED(aWidget->GetClientData(clientData))) {
     view = (nsIView*)clientData;