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

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https://hg.mozilla.org/integration/gaia-central/rev/e4822b34a357
Author: tamarahills <thills@mozilla.com>
Desc: Merge pull request #25909 from tamarahills/bugfix/1078448

Bug 1078448 - Modify call_screen_window.js reloadWindow to not leak Call...

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https://hg.mozilla.org/integration/gaia-central/rev/a15b584927c9
Author: Tamara Hills <thills@mozilla.com>
Desc: Bug 1078448 - Modify call_screen_window.js reloadWindow to not leak CallScreen app instances. r=drs.

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https://hg.mozilla.org/integration/gaia-central/rev/38844206ba88
Author: Florin Strugariu <florin.strugariu@softvision.ro>
Desc: Merge pull request #26447 from davehunt/bug1074117-gallery

Bug 1074117 - Use expected conditions and optimise element lookups in gallery app object

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https://hg.mozilla.org/integration/gaia-central/rev/8ee272531ef9
Author: Dave Hunt <dave.hunt@gmail.com>
Desc: Bug 1074117 - Use expected conditions and optimise element lookups in email app object. r=fstrugariu
Bumping manifests a=b2g-bump