title: Twig render array key with a dash in it
body: <p>How do you render a value of the value of an array key when it has a dash in the name?</p>
  
  <p>I have this snippet:</p>
  
  <pre><code>$snippet = "
      {{ one }}
      {{ four['five-six'] }}
      {{ ['two-three'] }}
  ";
  
  $data = [
      'one' =&gt; 1,
      'two-three' =&gt; '2-3',
      'four' =&gt; [
          'five-six' =&gt; '5-6',
      ],
  ];
  
  $twig = new \Twig_Environment(new \Twig_Loader_String());
  echo $twig-&gt;render($snippet, $data);
  </code></pre>
  
  <p>The output is</p>
  
  <pre><code>1
  5-6
  Notice: Array to string conversion in path/twig/twig/lib/Twig/Environment.php(320) : eval()'d code on line 34
  </code></pre>
  
  <p>And it renders <code>four['five-six']</code> fine. But throws an error on <code>['two-three']</code>.</p>