added missing colons

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

@@ -157,9 +157,9 @@ this.docHelper = this.docHelper || (() => {
 		elements.forEach(element => {
 			getElementsInfo(win, element, elementsInfo);
 			setInfo(win, element, elementsInfo);
-			setInfo(win, element, elementsInfo, "first-letter");
-			setInfo(win, element, elementsInfo, "before");
-			setInfo(win, element, elementsInfo, "after");
+			setInfo(win, element, elementsInfo, ":first-letter");
+			setInfo(win, element, elementsInfo, ":before");
+			setInfo(win, element, elementsInfo, ":after");
 		});
 		return elementsInfo;
 	}