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

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https://hg.mozilla.org/integration/gaia-central/rev/4cff2039128e
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #13188 from AndreiH/bug932250

Bug 932250 - Write a test for context menu activity picker

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https://hg.mozilla.org/integration/gaia-central/rev/a90bdecc808d
Author: Andrei Hutusoru <andreihutusoru@P5069.(none)>
Desc: Bug 932250 - Write a test for context menu activity picker

Conflicts:
	tests/python/gaia-ui-tests/gaiatest/apps/ui_tests/app.py