[whatwg] Node inDocument

[Erik Arvidsson]

As we were looking at mutation events we realized that we would like
to expose whether a Node is in the document or not. Both WebKit and
Gecko have an O(1) way of determine this. Today, to do this in script
this is O(depth) which is clearly sub optimal.

We are therefore suggesting adding the following to Node idl:

readonly attribute boolean inDocument;

Has this been covered before? Is there a reason why we would not want
to do this?

erik