expanding on keyboard support

Cam, all

I put a simple change in to add activeElement to the Document interface in
struct.html. I see there things that we already pull out of HTMLDocument
and drop in our spec. with some modifications. One question I have is that
if we do not have a focused element in our SVG document do we go to the
parent document or leave it as I have it to return the root element.

There are a number of event handlers in the HTML5 Document Interface that
are designed to support keyboard:
http://www.w3.org/TR/html5/dom.html#the-document-object

 attribute EventHandler onfocus;

           attribute EventHandler onkeydown;
           attribute EventHandler onkeypress;
           attribute EventHandler onkeyup;

SVG events are of course specified in a more declarative way. We have what
appears to be a mapping table here in our spec.

https://svgwg.org/svg2-draft/interact.html#SVGEvents

Should I add the keyboard events here?

Also, I noticed we still use activate. Should we simply just have click()
like HTML?

In IndieUI events we did not produce a device independent event for
activation as click is used to do the same thing although the name is not
device independent:
http://www.w3.org/TR/indie-ui-events/#RequestEvents

Cheers,
Rich