Bumping gaia.json for 4 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-central/rev/7c5532211028
Author: gitmai <mri@tid.es>
Desc: Merge pull request #15643 from gitmai/bug-835307-polish-l10n-properties

Bug 835307 - Polish l10n properties of Cost Control
r=salva

========

https://hg.mozilla.org/integration/gaia-central/rev/c21846f034f2
Author: mai <mri@tid.es>
Desc: Bug 835307 - Polish l10n properties of Cost Control

========

https://hg.mozilla.org/integration/gaia-central/rev/8e96c5bf884b
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #15964 from KevinGrandon/bug_966893_adjust_font_size

Bug 966893 - [Search] Adjust font size

========

https://hg.mozilla.org/integration/gaia-central/rev/175a5cae2513
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 966893 - [Search] Adjust font size
Bumping manifests a=b2g-bump