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

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https://hg.mozilla.org/integration/gaia-central/rev/46b331b7fa82
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #19525 from KevinGrandon/bug_1014180_test_agent_bump

Bug 1014180 - Update gaia_node_modules for test-agent bump

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https://hg.mozilla.org/integration/gaia-central/rev/b18197e41855
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1014180 - Update gaia_node_modules for test-agent bump r=julienw r=lightsofapollo
Bumping manifests a=b2g-bump