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

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https://hg.mozilla.org/integration/gaia-central/rev/6d36342917fe
Author: Greg Weng <snowmantw@gmail.com>
Desc: Merge pull request #13638 from yzen/937816

Bug 937816 - Making a software home button accessible.

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https://hg.mozilla.org/integration/gaia-central/rev/b9162c418dd8
Author: Yura Zenevich <yura.zenevich@gmail.com>
Desc: Bug 937816 - Making a software home button accessible.