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

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https://hg.mozilla.org/integration/gaia-central/rev/84806d46b65c
Author: Francisco Borja Salguero Castellano <borjasalguero@users.noreply.github.com>
Desc: Merge pull request #12935 from borjasalguero/uk_v1.2_sprint3_forward

Bug 927783 - [Messaging][Forward] Create action panel for deleting/forwa...

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https://hg.mozilla.org/integration/gaia-central/rev/592fc908accc
Author: borjasalguero <fbsc@tid.es>
Desc: Bug 927783 -  [Messaging][Forward] Per message context menu opens options/action menu (to incl. delete, forward) r=schung,rwldrn