Bumping gaia.json for 4 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/e936fd68f308
Author: Ghislain 'Aus' Lacroix <aus@noiseport.org>
Desc: Merge pull request #22229 from nullaus/bug1039631

bug 1039631 - Remove gradients from shared components and lockscreen.

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https://hg.mozilla.org/integration/gaia-central/rev/cd8b6eb24ada
Author: Ghislain 'Aus' Lacroix <aus@mozilla.com>
Desc: bug 1039631 - Remove gradients and patterns from shared components and lockscreen. ui-review=patryk

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https://hg.mozilla.org/integration/gaia-central/rev/6be700c6d29c
Author: vingtetun <21@vingtetun.org>
Desc: Merge pull request #22317 from vingtetun/landing-animation

Bug 1039519 - Implement a smooth transition to show/hide the rocketbar w...

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https://hg.mozilla.org/integration/gaia-central/rev/6cfda44e2dd7
Author: Vivien Nicolas <vnicolas@mozilla.com>
Desc: Bug 1039519 - Implement a smooth transition to show/hide the rocketbar when scrolling up/down a page. r=kgrandon
Bumping manifests a=b2g-bump