Bumping gaia.json for 2 gaia-1_3 revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-1_3/rev/6dfe034a0999
Author: Alive.Kuo <alegnadise@gmail.com>
Desc: Merge pull request #15144 from alivedise/bugzilla/946790_v1.3/app_modal_dialog_for_app_window

Bug 946790 - Standalone modal dialog for app window, r=timdream, a=1.3+

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https://hg.mozilla.org/integration/gaia-1_3/rev/130071306a1f
Author: Alive Kuo <alegnadise@gmail.com>
Desc: Bug 946790 - Standalone modal dialog for app window