There are a few minor differences between this and Mozilla's implementation:
(a) The type error messages were not hardcoded to the Performance class and were moved to Errors.msg instead.
(b) PerformanceMeasureOptions is used directly and doesn't use the the Maybe<> container class. I haven't found the reason yet, but PerformanceMeasureOptions is disallowed from having a copy constructor and without that, it isn't possible to use it with Maybe<>... There doesn't seem to be any problem with using it directly, though.
(c) Resist fingerprinting-pref changes were skipped.
Partially based on https://bugzilla.mozilla.org/show_bug.cgi?id=1762482
Since these are just interpreted comments, there's 0 impact on actual code.
This removes all lines that match /* vim: set(.*)tw=80: */ with S&R -- there are
a few others scattered around which will be removed manually in a second part.
FranklinDM
Moonchild
roytam1