SVG transform animations fills forwards

In the following example, the scale remains in effect after the 2 seconds have passed.

```
  // We have a polyfill bug here: fill 'none' is not being respected.
  element.animate([{transform: 'scale(1)'}, {transform: 'scale(3)'}], {duration: 2000, fill: 'none'});
```

This observed faulty behavior can be avoided by noting that transform is an SVG attribute; it must be added to svgProperties.
