Bumping gaia.json for 1 gaia-1_2 revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-1_2/rev/3e5a492e286f
Author: Arthur Chen <crh0716@gmail.com>
Desc: Merge pull request #12264 from crh0716/917238

Bug 917238 - Load network.json for supported network types r=evelyn(cherry picked from commit 4d28cf400b523e26d22b3a5ebe15a75764e48390)
Bug 895390 - Disable browser_privatebrowsing_cache.js for too many intermittent failures. a=test-only
Bug 914541 - Assign higher priority for mozapptype=inputmethod. r=fabrice, a=koi+
bug 803531: renew authenticode certificates in september 2013 - update authenticode issuer in tree. r=rstrong, a=lsblakk
Bug 917242 - Symbolize ASan traces in automation. r=ted, a=akeybl.