Added utility function for figuriong out if event is from child [HFP-436]

js/h5p-x-api-event.js

@@ -248,6 +248,16 @@ H5P.XAPIEvent.prototype.getContentXAPIId = function (instance) {
   return xAPIId;
 };
 
+/**
+ * Check if this event is sent from a child (i.e not from grandchild)
+ *
+ * @return {Boolean}
+ */
+H5P.XAPIEvent.prototype.isFromChild = function () {
+  var parentId = this.getVerifiedStatementValue(['context', 'contextActivities', 'parent', 0, 'id']);
+  return !parentId || parentId.indexOf('subContentId') === -1;
+}
+
 /**
  * Figure out if a property exists in the statement and return it
  *