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

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https://hg.mozilla.org/integration/gaia-central/rev/0770bf3d0436
Author: Jose M. Cantera <jmcanterafonseca@gmail.com>
Desc: Merge pull request #18742 from jmcanterafonseca/pages_as_shared_resource

Bug 1001370 - Add a new type of shared element (pages) for the build sys...

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https://hg.mozilla.org/integration/gaia-central/rev/40a863e4d737
Author: Jose M. Cantera <jmcanterafonseca@gmail.com>
Desc: Bug 1001370 - Add a new type of shared element (pages) for the build system
Bumping manifests a=b2g-bump