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

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https://hg.mozilla.org/integration/gaia-central/rev/fcfa04f8cba9
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Merge pull request #12187 from pivanov/bug-911968

Bug 911968 - [HD]Center rotation point of refresh icon off

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https://hg.mozilla.org/integration/gaia-central/rev/3f8fd5b8c274
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Bug 911968 - [HD]Center rotation point of refresh icon off