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

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https://hg.mozilla.org/integration/gaia-1_4/rev/907e17d059ce
Author: Francisco Jordano <arcturus@ardeenelinfierno.com>
Desc: Merge pull request #21052 from arcturus/bug-1026474

Bug 1026474 - [dolphin][Contacts]No Error pop up when exporting contacts to SD card, while SD card is full. r=jmcf

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https://hg.mozilla.org/integration/gaia-1_4/rev/9313b5f6beed
Author: Francisco Jordano <arcturus@ardeenelinfierno.com>
Desc: Bug 1026474 - [dolphin][Contacts]No Error pop up when exporting contacts to SD card, while SD card is full.
Bumping manifests a=b2g-bump