Replace HTMLMediaElement::isVideo() with isHTMLVideoElement

Source/core/html/shadow/MediaControlElements.cpp

Index: Source/core/html/shadow/MediaControlElements.cpp
diff --git a/Source/core/html/shadow/MediaControlElements.cpp b/Source/core/html/shadow/MediaControlElements.cpp
index 5e0437684f1e317363d5768406afd98078b9227b..2fcd4b1a9a7fd1d6e9d8dc62d4761a69b4d7d3a8 100644
--- a/Source/core/html/shadow/MediaControlElements.cpp
+++ b/Source/core/html/shadow/MediaControlElements.cpp
@@ -704,7 +704,7 @@ void MediaControlTextTrackContainerElement::updateDisplay()
     // 1. If the media element is an audio element, or is another playback
     // mechanism with no rendering area, abort these steps. There is nothing to
     // render.
-    if (!mediaElement().isVideo())
+    if (isHTMLAudioElement(mediaElement()))
         return;
 
     // 2. Let video be the media element or other playback mechanism.