[css-animations] Remove issue proposing alternative syntax for times in animation shorthand, which is no longer practical at this point.

Author: dbaron

css-animations/Overview.html

@@ -1470,10 +1470,6 @@ <h3 id=animation-shorthand-property><span class=secno>4.10. </span> The
    second value in each &lt;single-animation&gt; that can be parsed as a
    <var>&lt;time&gt;</var> is assigned to animation-delay.
 
-  <p class=issue> An alternative proposal is to accept the font shorthand
-   approach of using a "/" character between the values of the same type.
-   e.g. 2s/4s would mean a duration of 2 seconds and a delay of 4 seconds.
-
   <p class=issue> Need to also explain how order is important in terms of
    animation-name versus keywords, and probably also adjust the canonical
    order to match.

css-animations/Overview.src.html

@@ -1057,11 +1057,6 @@ <h3 id="animation-shorthand-property">
 		is assigned to animation-delay.
 	</p>
 
-	<p class="issue">
-		An alternative proposal is to accept the font shorthand approach 
-		of using a "/" character between the values of the same type. 
-		e.g. 2s/4s would mean a duration of 2 seconds and a delay of 4 seconds.
-
 	<p class="issue">
 		Need to also explain how order is important in terms of animation-name
 		versus keywords, and probably also adjust the canonical order to