OneLineConditional auto-correct produces incorrect code

[jonas054]

In #2885, auto-correct functionality was added to Style/OneLineConditional, but it needs tweaking.
@lumeet will you take a look?

Expected behavior

if ARGV.size > 0 then puts 'a' else puts 'b' end

auto-corrected to

ARGV.size > 0 ? (puts 'a') : (puts 'b')

or possibly that no change is made in complicated cases where the AST would be changed.

Actual behavior

if ARGV.size > 0 then puts 'a' else puts 'b' end

auto-corrected to

ARGV.size > 0 ? puts 'a' : puts 'b'

which is a syntax error.

Steps to reproduce the problem

rubocop -a file.rb

RuboCop version

$ rubocop -V
0.38.0 (using Parser 2.3.0.6, running on ruby 2.3.0 x86_64-linux)

and also current master, 7d10599.