remove is not ground check

Author: Alex1005a

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -4265,8 +4265,7 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
                     )
                   case _ =>
                     mapOver(t)
-              if !formal.isGround
-                && (formal.simplified `ne` formal)
+              if (formal.simplified `ne` formal)
                 && (pt1 `ne` pt)
                 && (pt1 ne sharpenedPt) then
                 val approxRes = wildApprox(pt1.resultType)