Dumper: JS for nette-toggle doesn't collide with SVG

When I had SVG on page (generated with [Raphael.js](https://github.com/DmitryBaranovskiy/raphael/) library), clicking on the element fired error in inlined `dumper.js`, because `elem.classList` of SVG element is instance of `SVGAnimatedString`, which doesn't have `indexOf()` method.