ISSUE-39 cooperate with WAI-ARIA \'politeness\' (from public comments)

We had some very informative discussions with the a11y experts. As is 
documented in http://www.w3.org/TR/2006/WD-aria-state-20060926/ WAI-ARIA 
politeness is for web content, and as discussed at the f2f, it's 
particularly useful in complex web content such as mashups. If we were 
developing any recommendations for embedding security context indicators 
in content, and differentiating different regions of content in terms of 
security context, this might be useful. But we're explicitly staying away 
from that, for reasons ranging from spoofability to confusion. So I'm 
closing this issue. I'm sure if any new proposals come in that this 
applies to, we'll remember and address this.