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

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https://hg.mozilla.org/integration/gaia-central/rev/11d7935dfac6
Author: Min-Zhong "John" Lu <mnjul@users.noreply.github.com>
Desc: Merge pull request #20653 from mnjul/bug_1025845_lockscreen_mediaplayer_widget

Bug 1025845 - [VsD Refresh] Lockscreen Visual Refresh > Media Player widget icons wrong. r=timdream

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https://hg.mozilla.org/integration/gaia-central/rev/a4b0cad49e41
Author: John Lu [:mnjul] <jlu@mozilla.com>
Desc: Bug 1025845 - [VsD Refresh] Lockscreen Visual Refresh > Media Player widget icons wrong

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https://hg.mozilla.org/integration/gaia-central/rev/6ec4310f6b59
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #20999 from KevinGrandon/land_bug_1027271

Bug 1027271 - [Rocketbar] banner becomes transparent occasionally when transitioning to browser

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https://hg.mozilla.org/integration/gaia-central/rev/1f8d16515e05
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1027271 - [Rocketbar] banner becomes transparent occasionally when transitioning to browser, by vingtetun r=etienne
Bumping manifests a=b2g-bump