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

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https://hg.mozilla.org/integration/gaia-central/rev/8c179b567c5e
Author: George <georgeiscoming@gmail.com>
Desc: Merge pull request #15283 from cctuan/956004-2

Bug 956004 - define a marco for node.js command

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https://hg.mozilla.org/integration/gaia-central/rev/cd3e2a885ae5
Author: cctuan <georgeiscoming@gmail.com>
Desc: Bug 956004 - define a marco for node.js command

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https://hg.mozilla.org/integration/gaia-central/rev/81903ff8f314
Author: EragonJ <eragonj@eragonj.me>
Desc: Revert "Merge pull request #14836 from EragonJ/bug-948847"

This reverts commit 1bd937c8c110788fcaec7deefe5f3367def18a42, reversing
changes made to 0bc133e32567bcf6aea7a7bff3b5fb7cde08fdfd.