Fix #3083: Check that all named parts of locally inferred types are d…

[odersky]

…efined.

[dottybot]

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[smarter]

We still get some weird errors in cases where we don't do result type inference:

trait Literal {
  type G
}

trait Addition { self: Literal =>
  def foo: G
}

object Test {
  def expression(adder: Addition) = {
    println(adder.foo)
  }
}

-- [E007] Type Mismatch Error: try/i3083.scala:11:18 ---------------------------
11 |    println(adder.foo)
   |            ^^^^^^^^^
   |            found:    adder.G
   |            required: Any
   |            

Also, I think we hhould have an additional pos test which is identical to https://github.com/dotty-staging/dotty/blob/6dac50abec83892a54d9c69eeab545e0484c1e27/tests/neg/i3083.scala but with adder: Addition replaced by adder: Addition & Literal to make sure that this continue working.