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

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https://hg.mozilla.org/integration/gaia-central/rev/a491e07757d7
Author: lissyx <lissyx+github@lissyx.dyndns.org>
Desc: Merge pull request #24216 from lissyx/bug1068860

Bug 1068860 - Allow ModalDialog to display pure strings r=gandalf

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https://hg.mozilla.org/integration/gaia-central/rev/d91ea3143e02
Author: Alexandre Lissy <lissyx+github@lissyx.dyndns.org>
Desc: Bug 1068860 - Allow ModalDialog to display pure strings r=gandalf

We may need to have to display strings that are not localized and for
which it does not make sense to have localization at all. This happens
for network-generated messages that we have to display to the user, on a
CDMA network for example.
Bumping manifests a=b2g-bump