assets/webapp.css: Disable common ligatures of Alegreya font
The Alegreya font we are using ships some ligatures producing confusing
text rendering, for instance the ligatures for ~
and some characters.
See for instance that bzr origin on staging, the ~
should not be
on top of the u
but before it.
So disable common ligatures with CSS.
Migrated from D7444 (view on Phabricator)