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

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https://hg.mozilla.org/integration/gaia-central/rev/9d5b6b01cf93
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #24496 from KevinGrandon/bug_1073608_usage_remove_extend

Bug 1073608 - [Usage] Remove Object.prototype.extend

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https://hg.mozilla.org/integration/gaia-central/rev/473dde421e6a
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1073608 - [Usage] Remove Object.prototype.extend r=salva

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https://hg.mozilla.org/integration/gaia-central/rev/675a6463b402
Author: Douglas Sherk <github@sherk.me>
Desc: Merge pull request #24638 from DouglasSherk/1076231-simpicker-racy-tests

Bug 1076231 - Fix racy unit tests in GaiaSimPicker. r=Rik

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https://hg.mozilla.org/integration/gaia-central/rev/bf3f7477de5a
Author: Doug Sherk <github@sherk.me>
Desc: Bug 1076231 - Fix racy unit tests in GaiaSimPicker. r=Rik
Bumping manifests a=b2g-bump