Mark upcoming WPT media-source test as WontFix

This test requires MP4 support in content_shell; that's not enabled by
default and breaks WPT imports.

TBR=chcunningham@chromium.org, wolenetz@chromium.org

No-Try: true
Change-Id: I3f176312cec46c8ef03dad5d40106c721b0f9723
Reviewed-on: https://chromium-review.googlesource.com/c/1365613Reviewed-by: Raphael Kubo da Costa <raphael.kubo.da.costa@intel.com>
Commit-Queue: Raphael Kubo da Costa <raphael.kubo.da.costa@intel.com>
Cr-Commit-Position: refs/heads/master@{#614361}

third_party/blink/web_tests/NeverFixTests

@@ -442,6 +442,7 @@ external/wpt/encrypted-media/clearkey-mp4-unique-origin.https.html [ WontFix ]
 external/wpt/encrypted-media/clearkey-mp4-waiting-for-a-key.https.html [ WontFix ]
 external/wpt/encrypted-media/clearkey-events-session-closed-event.https.html [ WontFix ]
 external/wpt/encrypted-media/clearkey-update-non-ascii-input.https.html [ WontFix ]
+external/wpt/media-source/mediasource-invalid-codec.html [ WontFix ]
 
 external/wpt/clipboard-apis/async-navigator-clipboard-basics.https.html [ WontFix ]
 external/wpt/css/CSS2/linebox/inline-formatting-context-010b.xht [ WontFix ]