webkitpy: Preserve XDG_DATA_DIRS in the environment passed to ServerProcess.
Created attachment 140376 [details] Patch
Besides the usual webkitpy suspects, I've also CC'ed a few people who work on ports which rely on jhbuild, as this patch should also remove the need to manually add some paths to XDG_DATA_DIRS in jhbuildrc.
Committed r116209: <http://trac.webkit.org/changeset/116209>