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

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https://hg.mozilla.org/integration/gaia-central/rev/818c13a8ae49
Author: Greg Weng <snowmantw@gmail.com>
Desc: Merge pull request #23248 from snowmantw/issue1057812

Bug 1057812 - Intermittent errors.JavascriptException: JavascriptExcepti...

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https://hg.mozilla.org/integration/gaia-central/rev/3cee526aab70
Author: Greg Weng <snowmantw@gmail.com>
Desc: Bug 1057812 - Intermittent errors.JavascriptException: JavascriptException: TypeError: d is undefined
Bumping manifests a=b2g-bump