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

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https://hg.mozilla.org/integration/gaia-central/rev/c38c45692f2d
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Merge pull request #10375 from davidflanagan/bug880843

Bug 880843: correctly predict low-frequency words r=es92

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https://hg.mozilla.org/integration/gaia-central/rev/6ea5825d54ea
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Bug 880843: correctly predict low-frequency words