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

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https://hg.mozilla.org/integration/gaia-1_4/rev/77f7fee6138b
Author: Julien Wajsberg <felash@gmail.com>
Desc: Merge pull request #17823 from julienw/987445-remove-vertical-align-middle-for-icon-buttons

Bug 987445 - [B2G][SMS]Delete button behavior intermittently unexpected ...
Bumping manifests a=b2g-bump