Bumping gaia.json for 3 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-central/rev/af85f6c1a201
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Merge pull request #15610 from gabrielesvelto/bug-947234-incremental-threads

Bug 947234 - Improve SMS app launch latency

========

https://hg.mozilla.org/integration/gaia-central/rev/e38acf13770d
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Bug 947234 - Quiet facebook-related errors that aren't really errors

========

https://hg.mozilla.org/integration/gaia-central/rev/b5f098318d37
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Bug 947234 - Render the threads incrementally
Bumping manifests a=b2g-bump
Bug 910903 - Stop requesting data when count >= 30 to prevent the main thread from starving the encoding thread. r=jsmith