Don't remove end of line when replacing selection at the end of line

[aesilevich]

Example code:

func foo() {
  let x = 10
}

How to reproduce:

1. Tap at the 'x' character on the line 2.
2. Move cursor past the end of the line 2.
3. Insert 'a' character

After step 3, the resulting code will be the following:

func foo() {
  let a}

It should be:

func foo() {
  let a
}