/usr/share/javascript/mootools/mootools.js is in libjs-mootools 1.4.2~debian1-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/javascript/mootools/mootools-core.min.js
/usr/share/javascript/mootools/mootools-core.min.js