Fix MediaSource.duration setter behavior to match the current spec.

Source/core/html/MediaController.cpp

 /*
  * Copyright (C) 2011 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 153 matching lines @@
     // If the new playback position is greater than the media controller duration, then set it
     // to the media controller duration.
     time = min(time, duration());
 
     // Set the media controller position to the new playback position.
     m_position = time;
     m_clock->setCurrentTime(time);
 
     // Seek each slaved media element to the new playback position relative to the media element timeline.
     for (size_t index = 0; index < m_mediaElements.size(); ++index)
-        m_mediaElements[index]->seek(time, exceptionState);
+        m_mediaElements[index]->seek(HTMLMediaElement::SkipAllowed, time, exceptionState);
 
     scheduleTimeupdateEvent();
 }
 
 void MediaController::unpause()
 {
     // When the unpause() method is invoked, if the MediaController is a paused media controller,
     if (!m_paused)
         return;
 
@@ skipping 287 matching lines @@
 }
 
 void MediaController::bringElementUpToSpeed(HTMLMediaElement* element)
 {
     ASSERT(element);
     ASSERT(m_mediaElements.contains(element));
 
     // When the user agent is to bring a media element up to speed with its new media controller,
     // it must seek that media element to the MediaController's media controller position relative
     // to the media element's timeline.
-    element->seek(currentTime(), IGNORE_EXCEPTION);
+    element->seek(HTMLMediaElement::SkipAllowed, currentTime(), IGNORE_EXCEPTION);
 }
 
 bool MediaController::isRestrained() const
 {
     ASSERT(!m_mediaElements.isEmpty());
 
     // A MediaController is a restrained media controller if the MediaController is a playing media
     // controller,
     if (m_paused)
         return false;
@@ skipping 105 matching lines @@
 {
     double now = WTF::currentTime();
     double timedelta = now - m_previousTimeupdateTime;
 
     if (timedelta < maxTimeupdateEventFrequency)
         return;
 
     scheduleEvent(EventTypeNames::timeupdate);
     m_previousTimeupdateTime = now;
 }