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

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https://hg.mozilla.org/integration/gaia-central/rev/d51baf92f327
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Merge pull request #15289 from davidflanagan/bug956172

Bug 956172: add a dismiss button to word suggestions in refactored keyboard r=janjongboom

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https://hg.mozilla.org/integration/gaia-central/rev/e23477e9d921
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Bug 956172: add a dismiss button to word suggestions in refactored keyboard

Don't clear the suggestions before we get new suggestions to avoid flashing
Bumping manifests a=b2g-bump