Wrong position for inlined type arguments

[nicolasstucki]

class Foo {
  inline def fun[T]: T = "".asInstanceOf[T]
  type X
  def foo = fun[X]
}

sbt:dotty> dotc Foo -Xprint:front -Yprint-pos -Ydebug-pos
[warn] Multiple main classes detected.  Run 'show discoveredMainClasses' to see the list
[info] Running (fork) dotty.tools.dotc.Main -classpath /Users/nicolasstucki/.ivy2/cache/org.scala-lang/scala-library/jars/scala-library-2.12.8.jar:/Users/nicolasstucki/GitHub/dotty/library/../out/bootstrap/dotty-library-bootstrapped/scala-0.14/dotty-library_0.14-0.14.0-bin-SNAPSHOT.jar Foo -Xprint:front -Yprint-pos -Ydebug-pos
result of Foo after frontend:
package <empty>@Foo<0..0> {
  class Foo() extends Object@Foo<6..6>@
    Foo<6..6>
  ()@Foo<6..6> { 
    inline def fun[
      T >: Nothing <: Any@Foo<29..29>@
        Foo[29..30]
    ]: T@Foo<33..34> = 
      ""@Foo<37..39>.asInstanceOf@
        Foo<37..52>
      [T@Foo<53..54>]@
        Foo<37..55>
       :T@Foo<33..34>@
        Foo<33..55>
    @Foo[14..25..55]
    type X >: Nothing <: Any@Foo<58..58>@
      Foo[58..63..64]
    def foo: Foo.this.X = 
      /* inlined from 
        this@Foo<77..77>.fun@
          Foo<77..80>
        [Foo.this.X@Foo<81..82>]@
          Foo<77..83>
       */ 
        {
          ""@Foo<37..39>.asInstanceOf@
            Foo<37..52>
          [Foo.this.X]@Foo<37..55> :
            Foo.this.X
          @Foo<77..83>
        }
      @Foo<77..83>
    @Foo[67..71..83]
  }@Foo[0..6..85]
}@Foo<0..85>

We can see that the position before inlining was [Foo.this.X@Foo.scala<81..82>] but after inlining it becomes [Foo.this.X] which is missing the position.

#6024 will add a way to test these positions.

This issue is related to #6026