Bumping gaia.json for 4 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/e78e79d48e89
Author: Arnau <arnau@arnaumarch.com>
Desc: Merge pull request #18180 from rnowm/994513

Bug 994513 - [VR][BB] update style for header buttons to use italics r=joan

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https://hg.mozilla.org/integration/gaia-central/rev/4c3817f6c6c7
Author: rnowm <arnau@arnaumarch.com>
Desc: Bug 994513 - [VR][BB] update style for header buttons to use italics

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https://hg.mozilla.org/integration/gaia-central/rev/01fbddbea1a9
Author: Julien Wajsberg <felash@gmail.com>
Desc: Merge pull request #18106 from julienw/993944-fix-async-storage-mock-mess

Bug 993944 - [DIaler][Messages] Unify the use of the async storage mock ...

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https://hg.mozilla.org/integration/gaia-central/rev/be8825c707d6
Author: Julien Wajsberg <julien@mozilla.com>
Desc: Bug 993944 - [DIaler][Messages] Unify the use of the async storage mock r=rik,schung

Also converts the use of a real asyncStorage to the mock.
Bumping manifests a=b2g-bump