What is the purpose of Antlr package in Visual Studio 2013 ASP.NET project?
Solution 1:
It is a transitive dependency declared in the WebGrease package, where it is used for a CSS lexer and parser.
Solution 2:
Also relevant for Visual Studio 2015 (ASP.NET MVC 5)
Bundling and minification in the ASP.Net templates is implemented in Microsoft.AspNet.Web.Optimization, which depends upon WebGrease, which itself depends upon Antlr.
So if you want to take advantage of ASP.Net template's built-in bundling and minification, you need them all.