removed unneeded whitespace

lib/single-file/css-rules-minifier.js

@@ -112,7 +112,7 @@ this.cssMinifier = this.cssMinifier || (() => {
 				const ruleSelectorText = ruleInfo.selectorsText[selectorTextIndex];
 				if (ruleInfo.matchedSelectors.has(ruleSelectorText)) {
 					if (selectorText) {
-						selectorText += ", ";
+						selectorText += ",";
 					}
 					newSelectors.push(ruleInfo.selectors[selectorTextIndex]);
 					newSelectorsText.push(ruleSelectorText);