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

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https://hg.mozilla.org/integration/gaia-central/rev/dfdfefd09d30
Author: Wilson Page <wilsonpage@me.com>
Desc: Merge pull request #18893 from verchaswa/Bug975558_Camera_Madai_Visual_Design_Self_Timer

[Bug975558][Camera][Madai]Visual Design Self-Timer

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https://hg.mozilla.org/integration/gaia-central/rev/f83f09d58d27
Author: verchaswa.sharma <verchaswa.sharma@lge.com>
Desc: [Bug975558][Camera][Madai]Visual Design Self-Timer
Bumping manifests a=b2g-bump