Prefs can be set with `./mach run --setpref foo=bar` or in the ~/.mozbuild/machrc file as: [runprefs] foo=bar MozReview-Commit-ID: HO3tdFi9ffi
Prefs can be set with `./mach run --setpref foo=bar` or in the ~/.mozbuild/machrc file as: [runprefs] foo=bar MozReview-Commit-ID: HO3tdFi9ffi