fixed method not found issue

lib/single-file/css-minifier.js

@@ -35,7 +35,7 @@ this.cssMinifier = this.stylesMinifier || (() => {
 				if (styleElement.sheet) {
 					let mediaInfo;
 					if (styleElement.media && styleElement.media != "all") {
-						mediaInfo = mediaAllInfo.get(styleElement.media);
+						mediaInfo = mediaAllInfo.medias.get(styleElement.media);
 					} else {
 						mediaInfo = mediaAllInfo;
 					}