Type extension doesn't work for SVG elements

[jails]

Hi, for an unknown reason the following spec (which passes on Chrome) doesn't pass with the polyfill.

it("creates a custom SVG element", function() {

    var MegaCircle = document.registerElement('mega-circle', {
      prototype: Object.create(SVGCircleElement.prototype),
      extends: 'circle'
    });

    var element = document.createElementNS("http://www.w3.org/2000/svg",  "circle",  "mega-circle");
    expect(element instanceof MegaCircle).toBe(true);

  });

Using the polyfill, element still an instance of SVGCircleElement instead.

[WebReflection]

for various reasons, createElementNS is not implemented here and won't be implemented. I should probably throw and update the README. Apologies for any inconvenient

[shawnbot]

I'm really curious about this. Why won't createElementNS be implemented?

[WebReflection]

full of inconsistencies across platform and not worth the effort. PR with tests and specifications coverage welcome.

[edit] and it shoud be suported by all current target devices