[css-animations] Clarify handling of animation-iteration-count:0

Author: Sylvain Galineau

css-animations/Overview.bs

@@ -513,14 +513,21 @@ The 'animation-iteration-count' property</h3>
 
 		<dt><dfn><<number>></dfn>
 		<dd>
-			The animation will repeat the specified number of times.
+			<p>The animation will repeat the specified number of times.
 			If the number is not an integer,
 			the animation will end partway through its last cycle.
-			Negative numbers are invalid.
-
-			A value of ''0'' is valid and,
-			similar to an 'animation-duration' of ''0s'',
-			causes the animation to occur instantaneously.
+			Negative numbers are invalid. 
+
+			<p>A value of ''0'' is valid and, similar to an 'animation-duration' 
+			of ''0s'', causes the animation to occur instantaneously. 
+			Specifically, if 'animation-fill-mode' is set to ''backwards'' or 
+			''both'', the first frame of the animation, as defined by 
+			'animation-direction', will be displayed during the 
+			'animation-delay'. Then the last frame of the animation, 
+			as defined by 'animation-direction', will be displayed if 
+			'animation-fill-mode' is set to ''forwards'' or ''both''. 
+			If 'animation-fill-mode' is set to ''animation-fill-mode/none'' then the animation has 
+			no effect though animation events still fire.
 	</dl>