Don't use transmute to create PaintOrder values
Don't use transmute to create PaintOrder values

I checked that rustc optimises the code just as well as with the transmute.

https://rust.godbolt.org/z/w6UJN4

KiChjang/servo,splav/servo,splav/servo,KiChjang/servo,splav/servo,splav/servo,KiChjang/servo,KiChjang/servo,splav/servo,splav/servo,KiChjang/servo,splav/servo,splav/servo,splav/servo,KiChjang/servo,KiChjang/servo,KiChjang/servo,splav/servo,KiChjang/servo,KiChjang/servo