[whatwg] Expose event.dataTransfer.files accessor to allow file drag and drop

[Noel Gordon]

> PROPOSAL
>
> When the user drags-and-drops files onto a web page, we should expose
> those files to the page via a "files" accessor on the dataTransfer
> property of the event object.  This feature is consistent with HTML
> 5's security model for drag and drop.

I wasn't clear on this part -- how is the proposal consistent with the HTML5
drag drop security model?

~noel