[css-variables] Add issue about animation.

Author: tabatkins

css-variables/Overview.html

@@ -150,7 +150,12 @@ <h2 id="introduction" data-level="1"><span class="secno">1 </span>
 	which are used to define <a data-autolink="link" href="#cascading-variable">variables</a>.
 
 </p><table class="propdef"><tbody><tr><th>Name:</th><td><dfn id="var-">var-*</dfn></td></tr><tr><th>Value:</th><td>[ <a data-autolink="link" class="production" href="#value-production"><var>&lt;value&gt;</var></a> | <a data-autolink="link" class="production" href="#cdo-production"><var>&lt;CDO&gt;</var></a> | <a data-autolink="link" class="production" href="#cdc-production"><var>&lt;CDC&gt;</var></a> ]+</td></tr><tr><th>Initial:</th><td>(nothing, see prose)</td></tr><tr><th>Applies to:</th><td>all elements</td></tr><tr><th>Inherited:</th><td>yes</td></tr><tr><th>Computed value:</th><td>specified value with variables substituted (but see prose for "invalid variables")</td></tr><tr><th>Media:</th><td>all</td></tr><tr><th>Animatable:</th><td>no</td></tr></tbody></table>
-<p>	A <dfn id="custom-property">custom property</dfn> is any property
+	<p class="issue">
+		Should variables have special animation behavior, 
+		such that they just never animate,
+		not even with the "just flip at 50% progress" like everything else?
+
+</p><p>	A <dfn id="custom-property">custom property</dfn> is any property
 	whose name starts with "var-",
 	and contains at least one additional character.
 	<a data-autolink="link" href="#custom-property">Custom properties</a> are solely for use by authors and users;

css-variables/Overview.src.html

@@ -79,6 +79,11 @@ <h2 id='defining-variables'>
 	Animatable: no
 	</pre>
 
+	<p class='issue'>
+		Should variables have special animation behavior, 
+		such that they just never animate,
+		not even with the "just flip at 50% progress" like everything else?
+
 	A <dfn>custom property</dfn> is any property
 	whose name starts with "var-",
 	and contains at least one additional character.