Reuse site instance only on window.open

atom/browser/api/atom_api_web_contents.cc

@@ -468,6 +468,7 @@ void WebContents::AddNewContents(content::WebContents* source,
   if (Emit("-add-new-contents", api_web_contents, disposition, user_gesture,
       initial_rect.x(), initial_rect.y(), initial_rect.width(),
       initial_rect.height())) {
+    AtomBrowserClient::CancelReuseRendererProcessForNewWindow();
     api_web_contents->DestroyWebContents();
   }
 }