Fixed an issue where the current window had no primary content area and the tree owner went off searching for one in other windows via the windows mediator but forgot to addref the result. b=58639, sr=scc@mozilla.org

xpfe/appshell/src/nsContentTreeOwner.cpp

@@ -141,7 +141,10 @@ NS_IMETHODIMP nsContentTreeOwner::FindItemWithName(const PRUnichar* aName,
       if(shellAsTreeItem)
          {
          if(fIs_Content)
+		    {
             *aFoundItem = shellAsTreeItem;
+            NS_ADDREF(*aFoundItem);
+            }
          else if(aRequestor != shellAsTreeItem.get())
             {
             // Do this so we can pass in the tree owner as the requestor so the child knows not