title: FabricJS - SVG serialization issue
body: <p>There seems to be an issue when trying to serialize a canvas that contains SVG elements. 
  I had created the following fiddle:
  <a href="https://jsfiddle.net/usrrdu/kr7uhb2n/60/" rel="nofollow noreferrer">JSFiddle</a></p>
  
  <p>Initially, I load an SVG from a string. This is working properly, the content is being displayed. </p>
  
  <pre><code>fabric.loadSVGFromString(svgString, function(objects, options) {
      var obj = fabric.util.groupSVGElements(objects, options);
      ...
  }
  </code></pre>
  
  <p>I added a button which exports the canvas to JSON, the it recreates the initial content using the JSON string. </p>
  
  <pre><code>var json = JSON.stringify(canvas);
  canvas.loadFromJSON(json);
  </code></pre>
  
  <p>If the button is being pressed, the SVG element is not being displayed correctly anymore, the initial element seems to be broken into several subelements which are not positioned correctly and also their size is changed as well.
  For some reason, the content is very small, but it can be seen better if the element is being resized</p>
  
  <p>This issues doesn't occur when using a "simpler" SVG, for instance, an SVG that only contains one symbol.</p>
  
  <p>I'm not sure what the problem is, whether the SVG string contains some elements that are not supported by Fabric, but then why is it being displayed properly the first time?</p>
  
  <p>Thanks! </p>