Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/b5843de56453
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #16132 from bebef1987/fix_video

Bug 970293 - Fix video tests intermittent fail

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https://hg.mozilla.org/integration/gaia-central/rev/49339ed37eb6
Author: Bebe <bebe@mozilla.ro>
Desc: Bug 970293 - Fix video tests intermittent fail

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "84907c4f2898397fe9a321f0f12d42546aed3071", 
+    "revision": "b5843de564536a1e0c5bc6fea436ef5829605059", 
     "repo_path": "/integration/gaia-central"
 }