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

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https://hg.mozilla.org/integration/gaia-central/rev/4ef060ed5c40
Author: Eitan Isaacson <eitan@monotonous.org>
Desc: Merge pull request #12766 from eeejay/bug-925164

Bug 925164 - Remove role and label from slider area.

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https://hg.mozilla.org/integration/gaia-central/rev/3417ff371169
Author: Eitan Isaacson <eitan@monotonous.org>
Desc: Bug 925164 - Remove role and label from slider area.