P2 removed IsTimerPrecisionReductionEnabled and thus removed the check for RFP
pref. While most ReduceTimePrecision* functions are fine with that because
GetTimerPrecisionType checks that, the two ReduceTimePrecision*RFP functions
miss the check.
This patch mainly cover the check for that two functions and rename them to
*RFPOnly since they only use RFP when the pref is on.
Depends on D64324
Differential Revision: https://phabricator.services.mozilla.com/D66734
--HG--
extra : moz-landing-system : lando
