title: Render a react element to a hidden area for measurement
body: <p>Does React provide a standard way to render a component outside of the normal flow?</p>
  
  <p>I would like to render a child element in a hidden area, measure its dimensions, and then use this information to alter what's being returned from the component's <code>render</code> method. Trying to use <code>React.render</code> throws an error:</p>
  
  <pre><code>Uncaught Invariant Violation: addComponentAsRefTo(...): Only a ReactOwner can have refs. You might be adding a ref to a component that was not created inside a component's `render` method
  </code></pre>