removed obsolete code

Former-commit-id: 682ceee10f7fa8e321317f1d22ee9c59fa6a6203

lib/single-file/single-file-util.js

@@ -147,9 +147,6 @@ this.singlefile.lib.util = this.singlefile.lib.util || (() => {
 				minifyHTML(doc, options) {
 					return modules.htmlMinifier.process(doc, options);
 				},
-				postMinifyHTML(doc) {
-					return modules.htmlMinifier.postProcess(doc);
-				},
 				minifyCSSRules(stylesheets, styles, mediaAllInfo) {
 					return modules.cssRulesMinifier.process(stylesheets, styles, mediaAllInfo);
 				},