Update transcript-tracer.js

transcript-tracer.js

@@ -587,7 +587,7 @@ function handleSelection() {
   // This is always defined here.
   var startWordIndexForTime = startWordElementForTime.dataset.ttWord;
   // But let's still get the `listIndex`.
-  var startWordListIndexForTime = startWordIndexForTime.listIndex;
+  var startWordListIndexForTime = startWordElementForTime.listIndex;
   var startSeconds = ttLinkedDataByMediaUrl[mediaUrl].wordTimings[startWordIndexForTime].startSeconds;
 
   console.log(startWordElement);