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

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https://hg.mozilla.org/integration/gaia-central/rev/b9a5b93b0068
Author: vingtetun <21@vingtetun.org>
Desc: Merge pull request #16809 from vingtetun/bug978780

Bug 978780 - position: fixed create an extra repaints when panning apps....

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https://hg.mozilla.org/integration/gaia-central/rev/eabcc067dd4e
Author: Vivien Nicolas <21@vingtetun.org>
Desc: Bug 978780 - position: fixed create an extra repaints when panning apps. r=crdlc
Bumping manifests a=b2g-bump