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

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https://hg.mozilla.org/integration/gaia-central/rev/4ebf31798917
Author: Rudy Lu <me@rudy.lu>
Desc: Merge pull request #21737 from RudyLu/keyboard/Bug998917-rtl_support_2

Bug 998917 - Keyboard keys are reversed in RTL locales.
r=stas

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https://hg.mozilla.org/integration/gaia-central/rev/69dad501d0a8
Author: Rudy Lu <me@rudy.lu>
Desc: Bug 998917 - Keyboard keys are reversed in RTL locales.
 - add dir="ltr" to body
Bumping manifests a=b2g-bump