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

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https://hg.mozilla.org/integration/gaia-central/rev/18f4d44024b0
Author: Fernando Rodríguez Sela <frsela@tid.es>
Desc: Merge pull request #11664 from lissyx/bug907629

Bug 907629 - Notify STK application when Settings is about to get killed, r=frsela

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https://hg.mozilla.org/integration/gaia-central/rev/5440da5e1422
Author: Alexandre Lissy <lissyx+github@lissyx.dyndns.org>
Desc: Bug 907629 - Notify STK application when Settings is about to get killed

It seems like doing it in the onunload callback is already too late, and
it makes the STK behaving wrongly.