[devtools] make a copy of the xvfb-run script so we can kill it properly
Since changeset a3d3bdd46463 we don't run firefox directly but through a
wrapper script. This meant that on stopping the test, we would kill
that wrapper script but leave the Xvfb server and firefox processes
running. So make a local copy of xvfb-run, and make it kill Xvfb when
it goes down, not just when its client exits.
Essayer le champ de recherche. Essayer des recherches comme "fiche
unmotachercher", ou encore "fiche wikiid index" ou "345".