Use correct indentation when inserting new line after an empty line

[aesilevich]

Example code:

func foo() {
  let x = 10

  let y = 20
}

How to reproduce:

1. Move cursor to the third (empty line)
2. Press the Return button

After pressing Return, the editor will insert new line without indentation. It should insert indentation spaces (two spaces) at the beginning of the new line.