Normative reference from ARIA 1.1 to UI Events KeyboardEvent key Values

The ARIA 1.1 aria-keyshortcuts property:

https://www.w3.org/TR/wai-aria-1.1/#aria-keyshortcuts

has a normative reference to  UI Events KeyboardEvent key Values. That 
document, however, is just a Working Draft. It is not permitted for a 
specification to advance to Recommendation while normative dependencies 
exist on specifications that have not themselves yet advanced to 
Recommendation. Do we expect this spec will reach Recommendation by the 
time we want ARIA to (April 2017)? If not we have a problem.

The quickest fix I can think of is to change the "must" to a "should" in 
the reference to that spec, in the sentence "Authors /MUST/ specify 
modifier keys exactly according to...". But that's a substantive change, 
that we would have to agree quickly because the formal transition to CR 
is scheduled for next week.

Michael