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

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https://hg.mozilla.org/integration/gaia-central/rev/64bce0f41677
Author: Yoshi Huang <allstars.chh@mozilla.com>
Desc: Merge pull request #18378 from svic/Bug_959059

Bug 959059: Abort shrinkUI if P2P link is gone. r=alive

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https://hg.mozilla.org/integration/gaia-central/rev/18f6ab3128c9
Author: Garner Lee <garner.lee@telekom.com>
Desc: Bug 959059: Abort Shrinking UI if P2P link is gone. r=alive
Bumping manifests a=b2g-bump