Simplify TextTrackCue::isActive

Source/core/html/track/CueTimeline.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/html/track/CueTimeline.h"
 
 #include "core/events/Event.h"
 #include "core/html/HTMLMediaElement.h"
 #include "core/html/HTMLTrackElement.h"
@@ skipping 46 matching lines @@
 {
     // Negative duration cues need to be treated in the interval tree as
     // zero-length cues.
     double endTime = std::max(cue->startTime(), cue->endTime());
 
     CueInterval interval = m_cueTree.createInterval(cue->startTime(), endTime, cue.get());
     m_cueTree.remove(interval);
 
     size_t index = m_currentlyActiveCues.find(interval);
     if (index != kNotFound) {
+        ASSERT(cue->isActive());
         m_currentlyActiveCues.remove(index);
         cue->setIsActive(false);
         // Since the cue will be removed from the media element and likely the
         // TextTrack might also be destructed, notifying the region of the cue
         // removal shouldn't be done.
         cue->removeDisplayTree(TextTrackCue::DontNotifyRegion);
     }
     updateActiveCues(mediaElement().currentTime());
 }
 
@@ skipping 255 matching lines @@
     if (!m_ignoreUpdate && mediaElement().inActiveDocument())
         updateActiveCues(mediaElement().currentTime());
 }
 
 DEFINE_TRACE(CueTimeline)
 {
     visitor->trace(m_mediaElement);
 }
 
 } // namespace blink