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

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https://hg.mozilla.org/integration/gaia-central/rev/6bb17d19d72e
Author: evanxd <itoyxd@gmail.com>
Desc: Merge pull request #18153 from evanxd/bug-987351

Bug 987351 - Migrate caldav_test.js to use new "view" code.

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https://hg.mozilla.org/integration/gaia-central/rev/c2dd4878e0df
Author: Evan Xd <itoyxd@gmail.com>
Desc: Bug 987351 - Migrate caldav_test.js to use new "view" code.
Bumping manifests a=b2g-bump