Bumping gaia.json for 4 gaia-central revision(s)

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https://hg.mozilla.org/integration/gaia-central/rev/302b622d781c
Author: gasolin <gasolin@gmail.com>
Desc: Merge pull request #11173 from gasolin/issue-887670sdp

Bug 887670 - [Test][System] Unit test for SpinDatePicker, r=alive

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https://hg.mozilla.org/integration/gaia-central/rev/67564a09ab9e
Author: gasolin <gasolin@gmail.com>
Desc: Bug 887670 - [Test][System] Unit test for SpinDatePicker

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https://hg.mozilla.org/integration/gaia-central/rev/ae21684b855f
Author: gasolin <gasolin@gmail.com>
Desc: Merge pull request #11152 from gasolin/issue-887670vp

Bug 887670 - [Test][System] Unit test for Value Picker, r=alive

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https://hg.mozilla.org/integration/gaia-central/rev/fd6ac317518a
Author: gasolin <gasolin@gmail.com>
Desc: Bug 887670 - [Test][System] Unit test for Value Picker