Macros: Test addition between ArrayLiteral and TupleLiteral

[caspiano]

Adds a few missing tests of the behaviour of addition between ArrayLiterals and TupleLiterals.

The following behaviour is tested...

{%
  a = [1, 2, 3, 4]
  b = {3, 4, 5, 6}
  c = a + b
  d = b + a
  puts c # => [1, 2, 3, 4, 3, 4, 5, 6]
  puts d # => {3, 4, 5, 6, 1, 2, 3, 4}
%}