Bumping gaia.json for 4 gaia-central revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/d5ba8e07d67e
Author: Greg Weng <snowmantw@gmail.com>
Desc: Merge pull request #15145 from JerryShih/bug-951812-gallery-release-gl-context

Bug 951812 - [Gallery] Release webgl context when we leave editor mode

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https://hg.mozilla.org/integration/gaia-central/rev/129cb4201228
Author: Jerry Shih <hshih@mozilla.com>
Desc: Bug 951812 - [Gallery] Release webgl context when we leave editor mode

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https://hg.mozilla.org/integration/gaia-central/rev/1083529ae8da
Author: Jose M. Cantera <jmcanterafonseca@gmail.com>
Desc: Merge pull request #15062 from jmcanterafonseca/bug_952504

Bug 952504 - [Messages] The Datastore error handling in contacts.js is w...

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https://hg.mozilla.org/integration/gaia-central/rev/b71997a7addd
Author: Jose M. Cantera <jmcanterafonseca@gmail.com>
Desc: Bug 952504 - [Messages] The Datastore error handling in contacts.js is wrong