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

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https://hg.mozilla.org/integration/gaia-central/rev/55774dacb8b4
Author: Michael Henretty <michael.henretty@gmail.com>
Desc: Merge pull request #21472 from mikehenrty/bug-994079-integration-test

Bug 994079 - integration tests for mozApps.getSelf

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https://hg.mozilla.org/integration/gaia-central/rev/5b8d2268c90c
Author: Michael Henretty <michael.henretty@gmail.com>
Desc: Bug 994079 - integration tests for mozApps.getSelf
Bumping manifests a=b2g-bump