make aria-owns to rearrange children

Hi.

aria-owns is used to define parent-child relationship [1]. The spec says
nothing how aria-owns affects on between-siblings relations, i.e. where
aria-owns children have to be in the hierarchy. So there's no way for the
author to control the ordering of explicit and aria-owns children. The idea
[2] was to let aria-owns to refer its own children to change the ordering.
For example,

<div role="grid"
<div role="row" aria-owns="c1 c2 c3 c4">
  <div role="gridcell" id="c1">cell1</div>
  <div role="gridcell" id="c2">cell1</div>
</div>
</div>

<!-- somewhere in the DOM -->
<div role="gridcell" id="c3">cell1</div>
<div role="gridcell" id="c4">cell1</div>

In this case role="row" would contain 4 cells in the order specified by
aria-owns.

If the idea looks reasonable then the spec could be changed this way

Insert after existing wording:
"The value <http://www.w3.org/WAI/PF/aria/terms#def_value> of the aria-owns
attribute <http://www.w3.org/WAI/PF/aria/terms#def_attribute> is a
space-separated list of IDREFS that reference one or more elements in the
document by ID."

something like:
"The order the referred elements listed in the value should be preserved
when their parent-child relationship is set. All explicit unreferred
children should be considered followed aria-owns elements."

Thanks.
Alexander.

[1] http://www.w3.org/WAI/PF/aria/states_and_properties#aria-owns
[2] https://bugzilla.mozilla.org/show_bug.cgi?id=1133213