Set value to SVG obj w/o error

See the issue https://github.com/riot/riot/issues/853

HTML

<script src="https://cdn.jsdelivr.net/g/[email protected]%28riot.min.js+compiler.min.js%29"></script>
<my-tag></my-tag>

<script type="riot/tag">
    <my-tag>
        <svg width="100" height="100">
            <rect name="rect1" riot-x="{ x }" riot-y="{ y }" riot-width="{ width }" height="50" />
        </svg>
        
        this.width = 100
        this.x = 10
        this.y = 20
        
        setInterval(function(){
          this.x = Math.random() * 20
          this.y = Math.random() * 20
          this.update()
        }.bind(this), 300)
        
 
    </my-tag>
</script>

JavaScript

/**
 * Riot.js is loaded from External Resources
 * https://cdn.jsdelivr.net/g/[email protected](riot.min.js+compiler.min.js)
 */
riot.mount('*')