This class was only added to do a reverse lookup of
RequestMethods enum to get its name (i.e. "GET") for Dart.
Since Dart is no longer supported by Http, method names
can just be retrieved with TypeScript's support for
enum name lookup,
i.e. RequestMethods[RequestMethods.GET] === 'GET',
making the RequestMethodsMap utility obsolete.
Closes#2904
51285666d8