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

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https://hg.mozilla.org/integration/gaia-central/rev/ece1e6123344
Author: Yura Zenevich <yura.zenevich@gmail.com>
Desc: Merge pull request #20147 from yzen/bug-1021708

Bug 1021708 - [Vertical Homescreen] Making search entry screen reader ac...

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https://hg.mozilla.org/integration/gaia-central/rev/79a166295c9e
Author: Yura Zenevich <yzenevich@mozilla.com>
Desc: Bug 1021708 - [Vertical Homescreen] Making search entry screen reader acesssible.
Bumping manifests a=b2g-bump