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

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https://hg.mozilla.org/integration/gaia-central/rev/a5d8735a5c6b
Author: Diego Marcos <diego.marcos@gmail.com>
Desc: Merge pull request #19920 from dmarcos/bug998362

Bug 998362 - First integration test using marionette js

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https://hg.mozilla.org/integration/gaia-central/rev/a8d5735cf323
Author: Diego Marcos <diego.marcos@gmail.com>
Desc: Bug 998362 - First integration test using marionette js
Bumping manifests a=b2g-bump