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

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https://hg.mozilla.org/integration/gaia-central/rev/5c151b3b7d59
Author: John Hu <johu@mozilla.com>
Desc: Merge pull request #15247 from huchengtw-moz/gallery/Bug_958681-parse-broken-image-file

Bug 958681 - [B2G][Gaia][Gallery] When a corrupt image is placed on the ..., r=djf

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https://hg.mozilla.org/integration/gaia-central/rev/5a04161d876e
Author: John Hu <johu@mozilla.com>
Desc: Bug 958681 - [B2G][Gaia][Gallery] When a corrupt image is placed on the device the gallery app can appear to continue loading indefinitely with no warning.
Bumping manifests a=b2g-bump