SI-7180 Fix regression in implicit scope of HK type alias.

We actually need to call normalize here, otherwise we don't
progress through #1 below.

    [infer implicit] scala.this.Predef.implicitly[Higher[Foo.Bar]] with pt=Higher[Foo.Bar] in object Foo
    1. tp=Foo.Bar tp.normalize=[A <: <?>]Foo.Bar[A] tp.dealias=Foo.Bar
    2. tp=Foo.Bar[A] tp.normalize=Box[A] tp.dealias=Box[A]
Merge pull request #2166 from retronym/ticket/7180

SI-7180 Fix regression in implicit scope of HK type alias.