Bug 1295844 - Add webm testing files to video decode suspend tests. r=gerald

Test files transcoded from gizmo.mp4 using:
ffmpeg -i gizmo.mp4 -vcodec vp9 -acodec opus gizmo.webm
ffmpeg -i gizmo.webm -vcodec copy -an gizmo-noaudio.webm

MozReview-Commit-ID: 4OB8G9NtS7A

--HG--
extra : rebase_source : e43b586371fae927d0e997064169e2e56de6b476

dom/media/test/gizmo-noaudio.webm^headers^

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

dom/media/test/gizmo.webm^headers^

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

dom/media/test/manifest.js

@@ -1430,7 +1430,9 @@ var gEMENonMSEFailTests = [
 // background tabs tests.
 var gDecodeSuspendTests = [
   { name:"gizmo.mp4", type:"video/mp4", duration:5.56 },
-  { name:"gizmo-noaudio.mp4", type:"video/mp4", duration:5.56 }
+  { name:"gizmo-noaudio.mp4", type:"video/mp4", duration:5.56 },
+  { name:"gizmo.webm", type:'video/webm; codecs="vp9,opus"', duration:5.56 },
+  { name:"gizmo-noaudio.webm", type:'video/webm; codecs="vp9"', duration:5.56 }
 ];
 
 function checkMetadata(msg, e, test) {

dom/media/test/mochitest.ini

@@ -423,6 +423,10 @@ support-files =
   gizmo.mp4^headers^
   gizmo-noaudio.mp4
   gizmo-noaudio.mp4^headers^
+  gizmo.webm
+  gizmo.webm^headers^
+  gizmo-noaudio.webm
+  gizmo-noaudio.webm^headers^
   huge-id3.mp3
   huge-id3.mp3^headers^
   id3tags.mp3