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

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https://hg.mozilla.org/integration/gaia-central/rev/cb4ca43d80f0
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #26419 from KevinGrandon/bug_1100305_browser_navigate_test

Bug 1100305 - [browser_navigate_landing_page_test.js] Re-enabling test by not sending keypress until after app window validation

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https://hg.mozilla.org/integration/gaia-central/rev/ffae7bbf0e7b
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1100305 - [browser_navigate_landing_page_test.js] Try re-enabling test by not sending keypress until after app window validation a=testonly
Bumping manifests a=b2g-bump