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

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https://hg.mozilla.org/integration/gaia-central/rev/993bb249c5df
Author: Cristian Rodriguez <crdlc@tid.es>
Desc: Merge pull request #12547 from crdlc/bug-lazy-dom-elements

Bug 922020 - Lazy load DOM nodes via HTML Import polyfill

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https://hg.mozilla.org/integration/gaia-central/rev/f00a92586b0e
Author: crdlc <crdlc@tid.es>
Desc: Bug 922020 - Lazy load Contacts DOM nodes via HTML Import polyfill