title: one-way binding does not work when binding item is object and modified dynamically
body: <p>please see the <a href="https://embed.plnkr.co/VRgaYlWlvHJUzftbiDg6/" rel="nofollow noreferrer">plnkr</a> for reviewing the code.</p>
  <p>I really new in AngularJS component. I write two simple AngularJS components with exactly same binding .</p>
  <pre><code> bindings: { value:'@', field:'@', object: '&lt;', callback: '&amp;' }   
  </code></pre>
  <p>I pass a Javascript object into my components by <code>object</code>. The <code>field</code> specifies the name of property in my JS object. Finally, <code>value</code> refers to the new value of  JS object's property.</p>
  <pre><code>object[field] = value
  </code></pre>
  <p>If the component does not clone the <code>object</code> in its controller, one-way binding does not work (see <code>onewaybindingfail</code> component in the plnkr). However, by cloning the <code>object</code> in component's controller everything is fine.</p>
  <p>I would like to know this behavior is expected? if yes, why? or I missing something?.</p>
  <p>Thanks for your help.</p>