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

========

https://hg.mozilla.org/integration/gaia-central/rev/58ce158d0ab5
Author: Florin Strugariu <bebef_1987@yahoo.com>
Desc: Merge pull request #20663 from zacc/bug_1026424_wallpaper

Bug 1026424 - Remove explicit frame switching from wallpaper test

========

https://hg.mozilla.org/integration/gaia-central/rev/bc8c9622c8e6
Author: Zac <zcampbell@mozilla.com>
Desc: Bug 1026424 - Remove explicit frame switching from wallpaper test
Bumping manifests a=b2g-bump