[DOM3 Events] textInput event should be removed

I'm not sure when, but at some point, it seems the textInput event changed
from being before the DOM was modified to being after the DOM was modified.
This means that the textInput event is now a strict subset of the input
event. We should instead remove the textInput event from the spec and add
the data and inputMethod properties to the existing input event.

Every browser already implements the input event and restricting to only
text inserting inputs is a single if-statement, 'if (event.data === "")'. I
don't see the benefits of having a special event. The cons are clear to me.
It's yet another event we fire on every key press, it broadens the platform
and it hurts performance (e.g. if you listen to both the textInput and
input events you need to do all the work of firing an event twice).

To add to the complication, the two existing implementations are fairly
incompatible. WebKit fires the event before the DOM is modified and matches
the case-sensitive "textInput". IE9 fires the event after the DOM is
modified and matches the case-sensitive "textinput".

The HTML spec already covers the input event, so my proposal is just to
remove the textInput event from DOM3 Events. Separately, we can get the
data and inputMethod properties specified in HTML.

Ojan