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

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https://hg.mozilla.org/integration/gaia-central/rev/1714372dc1cb
Author: Borja Salguero <borjasalguero@users.noreply.github.com>
Desc: Merge pull request #13631 from borjasalguero/common_library_download

Bug 937116 - [Download Manager] Create a utility library for common DOM ...

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https://hg.mozilla.org/integration/gaia-central/rev/7120b1206117
Author: borjasalguero <fbsc@tid.es>
Desc: Bug 937116 - [Download Manager] Create a utility library for common DOM Download operations r=kaze,crdlc

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https://hg.mozilla.org/integration/gaia-central/rev/6c7cfe729264
Author: Salvador de la Puente González <salva@unoyunodiez.com>
Desc: Merge pull request #13551 from lodr/bug-934921-null-sms

Bug 934921 - Making getSegmentInfoForTest() asynchronous
r=arcturus

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https://hg.mozilla.org/integration/gaia-central/rev/5f9b69fdb8f1
Author: lodr <salva@unoyunodiez.com>
Desc: Bug 934921 - Making getSegmentInfoForTest() asynchronous.