[web-animations-1][editorial] Export “inactive timeline”

Author: fantasai

web-animations-1/Overview.bs

@@ -636,7 +636,7 @@ A <a>timeline</a> may not always be able to return a meaningful <a>time
 value</a>, but only an <a>unresolved</a> time value.
 For example, it may be defined relative to a moment that has yet to occur,
 such as the firing of a document's load event.
-A <a>timeline</a> is considered to be <dfn lt="inactive timeline">inactive</dfn>
+A <a>timeline</a> is considered to be <dfn export lt="inactive timeline">inactive</dfn>
 when its <a>time value</a> is <a>unresolved</a>.
 
 A <a>timeline</a> is <dfn export lt="monotonically increasing timeline"