Wrong Web IDL type for URLs in Long Animation Frames API

[dontcallmedom-bot]

While crawling Long Animation Frames API, wrong Web IDL type for URLs:

• attribute sourceURL in interface PerformanceScriptTiming uses DOMString instead of recommended USVString for URLs

_{Cc @dontcallmedom @tidoust}

_{This issue was detected and reported semi-automatically by Strudy based on data collected in webref.}