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sebmarkbage
037b2e3088
At some point this trick was added to initialize the value first to NaN
and then replace them with zeros and negative ones.
This is to address the issue noted in
https://github.com/facebook/react/issues/14365 where these hidden
classes can be initialized to SMIs at first and then deopt when we
realize they're actually doubles.
However, this fix has been long broken and has deopted the profiling
build for years because closure compiler optimizes out the first write.
I'm not sure because I haven't A/B-tested this in the JIT yet but I
think we can use negative zero and -1.1 as the initial values instead
since they're not simple integers. Negative zero `===` zero (but not
Object.is) so is the same as far as our code is concerned. The negative
value is just `< 0` comparisons.
DiffTrain build for [94e4acaa14](https://github.com/facebook/react/commit/94e4acaa1477e65cac02ba86058cde0afe4c8f1f)