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

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https://hg.mozilla.org/integration/gaia-1_4/rev/e63567482f6a
Author: Alive.Kuo <alegnadise@gmail.com>
Desc: Merge pull request #18269 from alivedise/bugzilla/989087_v1.4/app-height-on-attention-screen

Bug 989087 - Fix fullscreen app height on attention screen coming, r=timdream

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https://hg.mozilla.org/integration/gaia-1_4/rev/8406db0ddbd4
Author: Alive Kuo <alegnadise@gmail.com>
Desc: Bug 989087 - Fix fullscreen app height on attention screen coming
Bumping manifests a=b2g-bump