Deleting for loop counter variable triggers warnings on reference even if the variable is defined in the parent scope

[vicchig]

1. Create a variable x = 123
2. Create a for loop for x in [1,2,3]
3. Insert print(x + 5) inside the body of the loop.
4. Remove the identifier x in the for loop.
5. Navigate off the loop statement and observe that the reference to x inside the print is marked with a warning even though it should not be because x is still declared outside of the loop in its parent scope.

Related: #565