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

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https://hg.mozilla.org/integration/gaia-central/rev/6b8f72fc133b
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #22587 from KevinGrandon/bug_1049678_wc_text_content

Bug 1049678 - [GaiaGrid] Remove textContent workaround

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https://hg.mozilla.org/integration/gaia-central/rev/ef49448d1ede
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1049678 - [GaiaGrid] Remove textContent workaround r=wilsonpage
Bumping manifests a=b2g-bump