It's MIT licensed. Thanks Prism developers!
https://bugzilla.gnome.org/show_bug.cgi?id=738475
8968687 Add Prism syntax highlighting in view source mode
embed/ephy-view-source-handler.c | 11 +-
src/Makefile.am | 6 +-
src/epiphany.gresource.xml | 2 +
src/resources/prism.css | 179 +++++++++
src/resources/prism.js | 745 ++++++++++++++++++++++++++++++++++++++
5 files changed, 938 insertions(+), 5 deletions(-)
Upstream: git.gnome.org