This is "MathJax single file" from:
 https://github.com/pkra/MathJax-single-file

Specifically the MMLSVG version from:
https://github.com/pkra/MathJax-single-file/tree/master/dist/MMLSVG

This was installed locally to allow off-line browsing.  The multi-file MathJax release cluttered up the source tree if installed locally.
