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

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https://hg.mozilla.org/integration/gaia-central/rev/755ad2936b1b
Author: Fabrice Desré <fabrice@desre.org>
Desc: Merge pull request #11107 from khuey/896825

Bug 896825: Call the closeCallback even if the close transition has been cancelled.

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https://hg.mozilla.org/integration/gaia-central/rev/ec55d3f26b76
Author: Kyle Huey <khuey@kylehuey.com>
Desc: Bug 896825: Call the closeCallback even if the close transition has been
cancelled. r=alive