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

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https://hg.mozilla.org/integration/gaia-central/rev/4be7104e4a58
Author: Ben Francis <ben@tola.me.uk>
Desc: Merge pull request #11791 from gasolin/issue-897917

Bug 897917 - HD: white rectangle in focused bookmark tab r=benfrancis

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https://hg.mozilla.org/integration/gaia-central/rev/40c702bb9506
Author: gasolin <gasolin@gmail.com>
Desc: Bug 897917 - HD: white rectangle in focused bookmark tab