Added issue reference for TODO, see https://github.com/phetsims/joist/issues/368, https://github.com/phetsims/joist/issues/64
Added issue reference for TODO, see https://github.com/phetsims/joist/issues/368, https://github.com/phetsims/joist/issues/64

phetsims/joist,phetsims/joist,phetsims/joist