Chrome Version       : Versie 48.0.2564.116 m

Bug javascript  IndexedDB:

Expected:
objectStore.get(key).onsuccess=function(event){ event.target !==null} 

Found: 
event.target is undefined

Probable cause: 
returned event is of type Event, not IDBEvent

N.B. the following works as expected:
objectStore.openCursor().onsuccess = function(event) {
  var key = event.target.result.key;
}