RedundantReturn autocorrect don't check that changed string it's valid ruby code

[akolomiychuk]

Example

def foo
  return :x => 1, :y => 2
end

Expected result

def foo
  { :x => 1, :y => 2 }
end

Actual result (syntax error)

def foo
  :x => 1, :y =>2
end

[akolomiychuk]

Rubocop version: 0.32.1 (using Parser 2.3.0.pre.2, running on ruby 2.2.0 x86_64-linux)