[css-animations] Add issue.

Author: dbaron

css-animations/Overview.bs

@@ -178,6 +178,15 @@ Animations</h2>
 
 	</div>
 
+	<p class="issue" id="issue-track-animation-state">
+	This specification should describe what information is part
+	of the state of running animations,
+	and how that information persists across changes to 'animation-name',
+	particularly when a name is repeated
+	within either the old or new value of 'animation-name'.
+	See <a href="https://lists.w3.org/Archives/Public/www-style/2016May/0111.html">www-style post</a> and other messages in the same thread.
+	</p>
+
 	Setting the 'display' property to ''display/none'' will terminate any running animation applied
 	to the element and its descendants. If an element has a 'display' of ''display/none'', updating
 	'display' to a value other than ''display/none'' will start all animations applied to the element