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

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https://hg.mozilla.org/integration/gaia-central/rev/2837b284fcee
Author: Aleh Zasypkin <aleh.zasypkin@gmail.com>
Desc: Merge pull request #22203 from azasypkin/bug-1044224-canvas-assets

Bug 1044224 - [Messages][Tests] Generate assets on the fly instead of loading it with XHR. Generating assets using canvas. r=julien

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https://hg.mozilla.org/integration/gaia-central/rev/9217adbe9747
Author: Aleh Zasypkin <azasypkin@mozilla.com>
Desc: Bug 1044224 - [Messages][Tests] Generate assets on the fly instead of loading it with XHR. Generating assets using canvas. r=julien
Bumping manifests a=b2g-bump