Changeset 284276@main change speech synthesis from experimental feature to always on. It also changed the speech synthesis backend, from flite2 to libspiel. Libspiel is not packaged in any distro yet. Since the feature was removed from experimental features, the Ubuntu and Debian upstream fails failed after 284276@main. The work around the build failure we disbaledspeech synthesis in the bots (-DENABLE_SPEECH_SYNTHESIS=OFF). Since speech synthesis is always on now, support for `libspiel` should be added to JHBuild minimal moduleset, for users that would like to build with this build system.
Pull request: https://github.com/webkit/webkit/pull/34696