Fix the bug by removing duplicated codeblock

See src/subParsers/outputModifiers.js

src/showdown.js

@@ -272,9 +272,6 @@ showdown.Converter = function (converterOptions) {
     text = text.replace(/~T/g, '~');
 
     // Run output modifiers
-    showdown.helper.forEach(globals.outputModifiers, function (ext) {
-      text = showdown.subParser('runExtension')(ext, text);
-    });
     text = parsers.outputModifiers(text, options, globals);
 
     return text;