removed unneeded code

lib/single-file/single-file-core.js

@@ -1013,7 +1013,6 @@ this.SingleFileCore = this.SingleFileCore || (() => {
 		}
 
 		static async processStylesheet(stylesheetContent, baseURI, options, inline, indexStyle, batchRequest) {
-			stylesheetContent = DomProcessorHelper.resolveStylesheetURLs(stylesheetContent, baseURI);
 			const urlFunctions = DomUtil.getUrlFunctions(stylesheetContent);
 			let indexVariable = 0;
 			await Promise.all(urlFunctions.map(async urlFunction => {