Bumping gaia.json for 3 gaia-central revision(s)

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https://hg.mozilla.org/integration/gaia-central/rev/bedd64e7287e
Author: James Lal <james@lightsofapollo.com>
Desc: Merge pull request #11727 from qdot/replacement-tests

Bug 892530 - Integration tests for notification replacement and creation

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https://hg.mozilla.org/integration/gaia-central/rev/84348409a3c3
Author: Kyle Machulis <kyle@nonpolynomial.com>
Desc: Bug 892530 - Integration tests for notification replacement and creation

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https://hg.mozilla.org/integration/gaia-central/rev/25a306ab9b3c
Author: Julien Wajsberg <felash@gmail.com>
Desc: Bug 908698 - Gaia unit tests: /bin/bash: ./xulrunner-sdk-26/bin/run-mozilla.sh: No such file or directory r=ochameau

Now we can define XULRUNNER_DIRECTORY from the command-line. If not defined, it
will use the default xulrunner-sdk-26.