title: $localStorage value got change with fabric js
body: <p>I saving polygon value inside angular $localStorage .</p>
  
  <p>Once fabric js draw the object . my $localStorage changed. </p>
  
  <pre><code>var arr = [{
          x: 81,
          y: 58
      }, {
          x: 221,
          y: 23
      }, {
          x: 247,
          y: 158
      }, {
          x: 100,
          y: 219
      }, {
          x: 81,
          y: 58
      }];
  
      if(!$localStorage.mask)
        $localStorage.mask = arr;
  </code></pre>
  
  <p>Is it a bug ?</p>
  
  <p>Here the <a href="http://plnkr.co/edit/GQnOIat1x1kMYvI3Vp4j?p=preview" rel="nofollow">plunker</a></p>