Bumping gaia.json for 3 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/6bf13f5f25a3
Author: Kyle Machulis <kyle@nonpolynomial.com>
Desc: Merge pull request #23400 from qdot/940647-browser-operator-variant

Bug 940647 - Move bookmark creation to operator variant app

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https://hg.mozilla.org/integration/gaia-central/rev/263527b1ee84
Author: Kyle Machulis <kyle@nonpolynomial.com>
Desc: Bug 940647 - Move bookmark creation to operator variant app

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https://hg.mozilla.org/integration/gaia-central/rev/4b7e019a546f
Author: KWierso <kwierso@gmail.com>
Desc: Revert "Bug 1054466 - Restore overflow menu via contextmenu. r=kgrandon" for Gu test failures

This reverts commit 838213d40dcba2e37b9e397c162aa5e44e9e64e7.
Bumping manifests a=b2g-bump