[css-animations-2] Update conditions for dispatching animationcancel to match animations level 1 and CSS transitions

Author: birtles

css-animations-2/Overview.bs

@@ -496,7 +496,8 @@ comparing the animation's phase before and after the sample as follows:
       <td><a>interval start</a></td>
     </tr>
     <tr>
-      <td>Not <a lt="idle phase">idle</a> &rarr;
+      <td><em>not</em> <a lt="idle phase">idle</a> and <em>not</em>
+          <a lt="after phase">after</a>&rarr;
           <a lt="idle phase">idle</a></td>
       <td><a idl>animationcancel</a></td>
       <td>The <a>active time</a> of the animation at the moment it was cancelled