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

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https://hg.mozilla.org/integration/gaia-central/rev/5fefe5cca49d
Author: Fernando Rodríguez Sela <frsela@tid.es>
Desc: Merge pull request #22619 from frsela/Bug861914_optgroup

Bug 861914 - [Browser] Forms are not displayed correctly, r=etienne

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https://hg.mozilla.org/integration/gaia-central/rev/81682cd9980a
Author: Fernando Rodriguez Sela <frsela@tid.es>
Desc: Bug 861914 - [Browser] Forms are not displayed correctly, r=etienne
Bumping manifests a=b2g-bump