`widenconst` before type check in SROA (#49642)
* `widenconst` before type check in SROA
These days, mutable structs can be `PartialStruct` if one of the
fields is annotated as `const`, so we need to widenconst before
this check.
* Update test/compiler/irpasses.jl
Co-authored-by: Shuhei Kadowaki <40514306+aviatesk@users.noreply.github.com>
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Co-authored-by: Shuhei Kadowaki <40514306+aviatesk@users.noreply.github.com>
