Compensate for getter transform in isSubType test

Getters transform `T` to `=> T`. This means that `=> T <: T`
might need to be true after getters. Observed in the wild
tree checking t938.scala after getters.

Author: odersky

src/dotty/tools/dotc/core/TypeComparer.scala

@@ -488,6 +488,9 @@ class TypeComparer(initctx: Context) extends DotClass with ConstraintHandling {
         case _ => tp2 isRef ObjectClass
       }
       compareJavaArray
+    case tp1: ExprType if ctx.phase.id >= ctx.gettersPhase.id =>
+      // getters might have converted T to => T, need to compensate.
+      isSubType(tp1.widenExpr, tp2)
     case _ =>
       false
   }