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

========

https://hg.mozilla.org/integration/gaia-central/rev/78d803e8450b
Author: Cristian Rodriguez <crdlc@tid.es>
Desc: Merge pull request #11802 from crdlc/bug-906536

Bug 906536 - [Homescreen] Big icons are overlaped over normal icons

========

https://hg.mozilla.org/integration/gaia-central/rev/ec025372cf11
Author: crdlc <crdlc@tid.es>
Desc: Bug 906536 - [Homescreen] Big icons are overlaped over normal icons