Added missing source map for underscore v1.6.0.
Added missing source map for underscore v1.6.0.


Former-commit-id: 92f7a5c85840b7627cf88e5b1b2e1db798009cfa
bfg-repo-cleaner-demos/jsdelivr-bfg-cleaned,bfg-repo-cleaner-demos/jsdelivr-bfg-cleaned,bfg-repo-cleaner-demos/jsdelivr-bfg-cleaned,bfg-repo-cleaner-demos/jsdelivr-bfg-cleaned