Fix all remaining negative zero bugs

[GarboMuffin]

My understanding is that the new compiler tries to reason about -0 a good bit but the use of (x||0) prevents it from fixing all of the bugs. This replaces that syntax with a jsexecute function that returns 0 only for NaN and leaves -0 unchanged.

Draft because:

• Need more performance testing. Brief initial testing found no slowdown in Linux in Scratch. @Geotale said this might even be faster in ideal conditions.
• Need some solid test cases to add.

Test @ https://experiments.turbowarp.org/fix-negative-zero/

[Tacodiva]

How does this effect performance?

[GarboMuffin]

My only datapoint so far is that isNaN(value) ? 0 : value made Linux in Scratch run 50% slower in Firefox whereas value === value ? value : 0 made it have no measurable difference compared to develop. Maybe next weekend or so I can look around a bit more. I'm particularly worried about performance of generator functions in Firefox which don't get into the highest tier of JIT so probably no inlining at all in that case.

[GarboMuffin]

some years ago i thought about gathering up some hundreds of projects so i can make a proper performance tracking and comparison system, though i never got around to that. would've been really cool to have these last weeks

[GarboMuffin]

it's also on https://experiments.turbowarp.org/fix-negative-zero/ if you were interested in testing anything yourself

Linux in Scratch, in Firefox, with warp timer, goes from around 36s -> around 40s to boot so it's measurable though less catastrophic than I expected. Chrome in the same configuration is maybe just a tiny bit slower but I think it's within noise.