stroke and fill must not close current sub path

Both `stroke` and `fill` on the 2d-Context close the current sub path, and start a new one.
However, the [spec](http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#dom-context-2d-stroke) states that "Paths, when filled or stroked, must be painted without affecting the current default path or any Path objects" 

Here's a fiddle that demonstrates the bug:
http://jsfiddle.net/76wxz/1/

In Ejecta, the Triangle is not filled however, because the call to stroke ends the first sub path.

I think to solve this issue, the subpath management would have to be refactored so that the `currentPath` is always part of the `paths` list