ClientRectList.item() usage is very low in Blink

Hi all,

http://dev.w3.org/fxtf/geometry/ says "The DOMRectList interface is
at-risk. The authors of this specification await feedback from
implementers if the item() function of DOMRectList is currently in use
on legacy interfaces. If there is no/not enough content to justify
DOMRectList, legacy interfaces must use sequences instead and
DOMRectList will be removed from this specification."

Chrome 43 reached the stable channel about a week ago, and it had a
use counter in Blink to answer this very question:
https://www.chromestatus.com/metrics/feature/timeline/popularity/694

Compare that to another use counter also in the same release:
https://www.chromestatus.com/metrics/feature/timeline/popularity/696

When usage rounds to zero as for ClientRectList.item(), it means that
<0.0001% of page loads are affected. This is no guarantee that
replacing ClientRectList with sequence<ClientRect> as the return value
of Element.getClientRects() and Range.getClientRects() would be safe,
but it's promising.

(Dirk Schulze suggested that I notify public-fx and www-style.)

Philip