/usr/share/gir-1.0/JSCore-1.0.gir is in libjavascriptcoregtk-1.0-dev 2.4.10-0ubuntu0.14.04.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/gir-1.0/JavaScriptCore-1.0.gir
/usr/share/gir-1.0/JavaScriptCore-1.0.gir