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

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https://hg.mozilla.org/integration/gaia-1_4/rev/07533a22a9fd
Author: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Desc: Merge pull request #22656 from evelynhung/issue-m044960-1.4

Bug 1044960 - hide startscreen if tab url was null

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https://hg.mozilla.org/integration/gaia-1_4/rev/7672254ec4cb
Author: Evelyn Hung <jj.evelyn@gmail.com>
Desc: Bug 1044960 - hide startscreen if tab url was null
Bumping manifests a=b2g-bump