Address review comments for the change to packMJfile.
Address review comments for the change to packMJfile.

Khan/MathJax-dev,dpvc/MathJax-dev,Khan/MathJax-dev,dpvc/MathJax-dev,dpvc/MathJax-dev,Khan/MathJax-dev,Khan/MathJax-dev,dpvc/MathJax-dev,dpvc/MathJax-dev,dpvc/MathJax-dev,Khan/MathJax-dev,Khan/MathJax-dev