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

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https://hg.mozilla.org/integration/gaia-central/rev/9178679dc405
Author: Francisco Jordano <arcturus@ardeenelinfierno.com>
Desc: Merge pull request #14168 from arcturus/bug-942140

Bug 942140 - [Settings] when invoked as an activity, we should have a cross instead of a back button and pressing it should move back to the caller

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https://hg.mozilla.org/integration/gaia-central/rev/b4567053da5c
Author: Francisco Jordano <arcturus@ardeenelinfierno.com>
Desc: Bug 942140 - [Settings] when invoked as an activity, we should have a cross instead of a back button and pressing it should move back to the caller