Bumping gaia.json for 2 gaia-central revision(s)

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https://hg.mozilla.org/integration/gaia-central/rev/a58a2144100e
Author: Yuren Ju <yurenju@gmail.com>
Desc: Merge pull request #11545 from yurenju/remove-offline

Bug 905608 - Remove build/offline-cache.js and make target for it r=@timdream

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https://hg.mozilla.org/integration/gaia-central/rev/518d0a317466
Author: Yuren Ju <yurenju@gmail.com>
Desc: Bug 905608 - Remove build/offline-cache.js and make target for it