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

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https://hg.mozilla.org/integration/gaia-central/rev/9b8fdefc90d4
Author: Jose M. Cantera <jmcanterafonseca@gmail.com>
Desc: Merge pull request #12788 from jmcanterafonseca/fix_fb_dialog

Bug 925602 - [B2G][Contacts] No error message is given when a loss of da...

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https://hg.mozilla.org/integration/gaia-central/rev/a356cb14000c
Author: Jose M. Cantera <jmcanterafonseca@gmail.com>
Desc: Bug 925602 - [B2G][Contacts] No error message is given when a loss of data connection occurs while importing Gmail contacts