Add [TypeChecking=Interface] to the TextTrack interface

Source/core/html/track/TextTrack.cpp

 /*
  * Copyright (C) 2011 Google Inc.  All rights reserved.
  * Copyright (C) 2011, 2012, 2013 Apple Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 207 matching lines @@
     // order. Otherwise, it must return null. When an object is returned, the
     // same object must be returned each time.
     // http://www.whatwg.org/specs/web-apps/current-work/#dom-texttrack-activecues
     if (m_cues && m_mode != disabledKeyword())
         return m_cues->activeCues();
     return nullptr;
 }
 
 void TextTrack::addCue(PassRefPtrWillBeRawPtr<TextTrackCue> prpCue)
 {
-    if (!prpCue)
-        return;
-
+    ASSERT(prpCue);
     RefPtrWillBeRawPtr<TextTrackCue> cue = prpCue;
 
     // TODO(93143): Add spec-compliant behavior for negative time values.
     if (std::isnan(cue->startTime()) || std::isnan(cue->endTime()) || cue->startTime() < 0 || cue->endTime() < 0)
         return;
 
     // 4.8.10.12.5 Text track API
 
     // The addCue(cue) method of TextTrack objects, when invoked, must run the following steps:
 
     // 1. If the given cue is in a text track list of cues, then remove cue from that text track
     // list of cues.
     TextTrack* cueTrack = cue->track();
     if (cueTrack && cueTrack != this)
         cueTrack->removeCue(cue.get(), ASSERT_NO_EXCEPTION);
 
     // 2. Add cue to the method's TextTrack object's text track's text track list of cues.
     cue->setTrack(this);
     ensureTextTrackCueList()->add(cue);
 
     if (cueTimeline() && m_mode != disabledKeyword())
         cueTimeline()->addCue(this, cue.get());
 }
 
 void TextTrack::removeCue(TextTrackCue* cue, ExceptionState& exceptionState)
 {
-    if (!cue)
-        return;
+    ASSERT(cue);
 
     // 4.8.10.12.5 Text track API
 
     // The removeCue(cue) method of TextTrack objects, when invoked, must run the following steps:
 
     // 1. If the given cue is not currently listed in the method's TextTrack
     // object's text track's text track list of cues, then throw a NotFoundError exception.
     if (cue->track() != this) {
         exceptionState.throwDOMException(NotFoundError, "The specified cue is not listed in the TextTrack's list of cues.");
         return;
@@ skipping 180 matching lines @@
 DEFINE_TRACE(TextTrack)
 {
     visitor->trace(m_cues);
     visitor->trace(m_regions);
     visitor->trace(m_trackList);
     TrackBase::trace(visitor);
     EventTargetWithInlineData::trace(visitor);
 }
 
 } // namespace blink