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

========

https://hg.mozilla.org/integration/gaia-central/rev/475d50d06d01
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #25585 from KevinGrandon/bug_1088700_vertical_home_smooth_scroll

Bug 1088700 - [VerticalHome] Use new CSSOM smooth scrolling implementation

========

https://hg.mozilla.org/integration/gaia-central/rev/144fb7d52981
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1088700 - [VerticalHome] Use new CSSOM smooth scrolling implementation r=kgrandon

========

https://hg.mozilla.org/integration/gaia-central/rev/71ced63a1362
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #25553 from KevinGrandon/bug_1089795_shb_open_invalid_type

Bug 1089795 - [System] Layout problem with SHB in open file error dialog

========

https://hg.mozilla.org/integration/gaia-central/rev/a5ad02a4d83a
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1089795 - [System] Layout problem with SHB in open file error dialog r=mhenretty
Bumping manifests a=b2g-bump