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

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https://hg.mozilla.org/integration/gaia-central/rev/9e00ea980c1d
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Merge pull request #15355 from mmalecki/remove-charging-attribute

Bug 960039 - [system] Remove `charging` attribute, r=timdream

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https://hg.mozilla.org/integration/gaia-central/rev/fa816693b78a
Author: Maciej Małecki <me@mmalecki.com>
Desc: Bug 960039 - [system] Remove `charging` attribute

Remove unused, non-standard `charging` attribute from the markup for the
battery icon.
Bumping manifests a=b2g-bump