Based on the provided text, it is difficult to determine what the website is about as most of the content consists of JavaScript code snippets and function definitions. However, it appears to be related to web performance measurement and optimization. It mentions functions like "performancemark" and "performancemeasure," which are used for collecting performance metrics. The code also includes references to browsers, polyfills, and window-related objects.
Without more information or additional context from the website's HTML, it is not possible to provide a comprehensive summary of what the site is about or its specific purpose.
