Remove incorrect type simplification #9019
Merged
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TypeOps#simplify
is supposed to produce a type=:=
the originaltype, but it replaced type variables created using
newTypeVar
by oneof their bound, this is wrong since that type variable might get
instantiated to a different type later. This simplification was added
in #2209 to prevent a pickling crash in tests/pos/i2152.scala but does
not appear to be needed anymore: an uninstantiated type variable being
preserved after typer is always wrong, so the underlying bug must have
been fixed since then.