revert unnecessary customizations of Blob.js & FileSaver.js

Per https://github.com/eligrey/Blob.js/pull/20
& https://github.com/eligrey/FileSaver.js/pull/63
The library author has deemed the existing /*! @source URL */ comments to be
sufficient attribution, and these already survive minification.

Refs ea591748edee4f8fe722274b71787ccf2b052c4a