SVG-related suggested text for ARIA 1.1 Requirements Note

Hi Michael,

Here are suggestions on how to incorporate the SVG work into the ARIA
requirements note [1].  One paragraph as an edit to your point #5 ("Allow
extensions to the WAI-ARIA suite") and then another new SVG-specific
point.  I'd also suggest re-arranging the list so the two immediately
follow the first point on adapting for HTML 5.

Allow extensions to the WAI-ARIA suite§
<http://w3c.github.io/aria/requirements/aria-requirements.html#allow-extensions-to-the-wai-aria-suite>

WAI-ARIA 1.0 was not designed with extensibility in mind.  It addressed
HTML documents and other text-based XML content.  Some communities have
requested features, however, that would require a substantial revision of
the ARIA technology to incoporate. WAI-ARIA 1.1 will allow, via process and
tools, extensions that inherit all the features of the core specification
plus add new ones, clearly distinguishing the shared core features from the
details that are specific to HTML or other languages.
Ensure compatibility with SVG accessibility features§
<http://w3c.github.io/aria/requirements/aria-requirements.html#allow-extensions-to-the-wai-aria-suite>

The core features of WAI-ARIA 1.1 will be generalizable to represent
default host language accessibility features in SVG.  The SVG 2
specification specifically adopts WAI-ARIA roles and other attributes into
that language.  Future extension specifications will provide more nuanced
ways to represent complex semantics in graphical documents.

As a general note, I would suggest that some of the other items are
currently vague to the point of being confusing.  While trying to remain
general, I think it might help to give some concrete examples.  E.g., for
the urgently-needed features based on web page usage, I assume this refers
to things like the "feed" role.  I'm not sure what the HTML 5 missing
features are.

[1]: http://w3c.github.io/aria/requirements/aria-requirements.html