Bug 1489102 - P4. Add flac in mp4 plain file test. r=bryce

Differential Revision: https://phabricator.services.mozilla.com/D5242

--HG--
extra : moz-landing-system : lando

dom/media/test/flac-sample.mp4^headers^

@@ -0,0 +1 @@
+Cache-Control: no-store

dom/media/test/manifest.js

@@ -313,6 +313,7 @@ var gPlayTests = [
   // It is necessary to parse the file to find an audio frame instead.
   { name:"flac-noheader-s16.flac", type:"audio/flac", duration:4.0 },
   { name:"flac-s24.flac", type:"audio/flac", duration:4.04 },
+  { name:"flac-sample.mp4", type:"audio/mp4; codecs=flac", duration:4.95 },
   // Ogg with theora video and flac audio.
   { name:"A4.ogv", type:"video/ogg", width:320, height:240, duration:3.13 },
 

dom/media/test/mochitest.ini

@@ -449,6 +449,8 @@ support-files =
   flac-s24.flac^headers^
   flac-noheader-s16.flac
   flac-noheader-s16.flac^headers^
+  flac-sample.mp4
+  flac-sample.mp4^headers^
   flac-sample-cenc.mp4
   flac-sample-cenc.mp4^headers^
   fragment_noplay.js