add support for Asynchronous Drawing Models (Bitmap and Windows Accelerated) about npapi-sdk HOT 7 CLOSED

Stuart, can you review this?

> -  NPDrawingModelCoreAnimation = 3,
> +  NPDrawingModelCoreAnimation = 3, /* DEPRECATED, DO NOT USE */

I disagree pretty strongly with this change; My understanding was that Safari 
never intends to support ICA (since they don't have the implementation 
constraints that make it problematic to support CA), and everyone was okay with 
that, so describing it as deprecated is actively misleading, and will confuse 
plugin vendors.

> +  NPDrawingModelAsyncBitmapSurface = 7,
> +#if defined(XP_WIN)
> +  NPDrawingModelAsyncWindowsDXGISurface = 8
...
> +  , NPNVsupportsAsyncBitmapSurfaceBool = 2005
> +#if defined(XP_WIN)
> +  , NPNVsupportsAsyncWindowsDXGISurfaceBool = 2006

Mismatching the numbers here seems like a very bad idea. I would like to see us 
use 2007 and 2008 here. Not only will this be less potentially confusing, but 
it makes it easy to add support variables for the original types later (just as 
we've needed to add a support variable for QD on the Mac). In fact, it seems 
like it wouldn't hurt to just go ahead and add them now, but I feel much less 
strongly about that than I do about aligning the numbers.

I'm on board re: NPDrawingModelCoreAnimation - I'll drop that comment from the 
patch.

Updated patch.

LGTM, thanks.