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

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https://hg.mozilla.org/integration/gaia-central/rev/1ed88f52df7b
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Merge pull request #13614 from etiennesegonzac/bug-936793-call-log-migration-hotfix

Bug 936793 - HOTFIXing a call log idb migration by hardening the Contacts.findByNumber method. r=ferjm

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https://hg.mozilla.org/integration/gaia-central/rev/397c778aa681
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Bug 936793 - HOTFIXing a call log idb migration by hardening the
Contacts.findByNumber method.