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

Source/core/html/MediaController.cpp

Index: Source/core/html/MediaController.cpp
diff --git a/Source/core/html/MediaController.cpp b/Source/core/html/MediaController.cpp
index 7835e2307a6efa23b6df4cd0c142aceec4d83362..13282bbf859b91dca0a36afb185d8f0253289ed7 100644
--- a/Source/core/html/MediaController.cpp
+++ b/Source/core/html/MediaController.cpp
@@ -171,7 +171,7 @@ void MediaController::setCurrentTime(double time, ExceptionState& exceptionState
 
     // 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();
 }
@@ -479,7 +479,7 @@ void MediaController::bringElementUpToSpeed(HTMLMediaElement* 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