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

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https://hg.mozilla.org/integration/gaia-central/rev/06c4eb678d25
Author: Carsten Book <tomcat@mozilla.com>
Desc: Merge pull request #25498 from pamadini/promise-timing-v2

Bug 1086528 - telephony_helper_test.js incorrectly uses Promises as a way to delay a test assertion. r=drs

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https://hg.mozilla.org/integration/gaia-central/rev/c2dd0845f6dc
Author: Paolo Amadini <paolo.mozmail@amadzone.org>
Desc: Bug 1086528 - telephony_helper_test.js incorrectly uses Promises as a way to delay a test assertion. r=drs

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https://hg.mozilla.org/integration/gaia-central/rev/eca7ce40da84
Author: Carsten Book <tomcat@mozilla.com>
Desc: Merge pull request #25483 from mancas/bug1088523

Bug 1088523 - [Follow-up][FTE][2.2] About Firefox OS page is missing Fir.... r=gandalf

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https://hg.mozilla.org/integration/gaia-central/rev/cf384e617f4c
Author: Manuel Casas Barrado <manuel.casasbarrado@telefonica.com>
Desc: Bug 1088523 - [Follow-up][FTE][2.2] About Firefox OS page is missing Firefox OS link / words in the welcome message
Bumping manifests a=b2g-bump