This adds in preferences for all the SM 39 available options (as
retrieved from Gecko), and uses the same defaults as Gecko. A few
properties are not supported yet, and incremental GC is still always
disabled regardless of the preference setting.
Source-Repo: https://github.com/servo/servo
Source-Revision: bc2237ea2ba3beac501ca4347b8118f3dccd9629
This PR mistakenly removed JIT enabling/disabling by preference:
https://github.com/servo/servo/pull/10342/files
Look for `get_pref`.
I'm putting the missing piece of code into the appropriate place in
script_runtime.rs
r? @KiChjang
Source-Repo: https://github.com/servo/servo
Source-Revision: bead9585000eed60394b20c7a8e3788284ea458a
