Unreviewed GTK build fix.

Add the build targets introduced in r140231 to the list.

* GNUmakefile.list.am:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@140239 268f45cc-cd09-0410-ab3c-d52691b4dbfc
diff --git a/Source/WebCore/GNUmakefile.list.am b/Source/WebCore/GNUmakefile.list.am
index 9dcdf03..75657ebb 100644
--- a/Source/WebCore/GNUmakefile.list.am
+++ b/Source/WebCore/GNUmakefile.list.am
@@ -3678,6 +3678,8 @@
 	Source/WebCore/html/track/TrackBase.h \
 	Source/WebCore/html/track/TrackEvent.cpp \
 	Source/WebCore/html/track/TrackEvent.h \
+	Source/WebCore/html/track/WebVTTElement.cpp \
+	Source/WebCore/html/track/WebVTTElement.h \
 	Source/WebCore/html/track/WebVTTParser.cpp \
 	Source/WebCore/html/track/WebVTTParser.h \
 	Source/WebCore/html/track/WebVTTToken.h \