Auto merge of #17250 - cbrewster:unwrap_constructor, r=jdm

Unwrap function before calling IsConstructor

`IsConstructor` returns true for all wrappers that are callable. Wrapped
arrow functions are callable and thus `IsConstructor` will return true
if given one; however, if we unwrap the arrow function, `IsConstructor`
will return false. The latter is the correct behavior here.

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