Bumping gaia.json for 4 gaia-central revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/3c31ce933f48
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Merge pull request #14912 from davidflanagan/bug939679

Bug 939679: compute the right camera preview size on HD devices r=dmarcos

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https://hg.mozilla.org/integration/gaia-central/rev/f1092ff15f42
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Bug 939679: compute the right camera preview size on HD devices

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https://hg.mozilla.org/integration/gaia-central/rev/84146f63920f
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Merge pull request #15051 from davidflanagan/bug939962

Bug 939962: set the willReadFrequently flag when creating the 2D context... r=snorp

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https://hg.mozilla.org/integration/gaia-central/rev/4452a66717b2
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Bug 939962: set the willReadFrequently flag when creating the 2D context for saving an edited image
Bumping gaia.json for 2 gaia-central revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/376444b1a858
Author: Gareth Aye <gaye@mozilla.com>
Desc: Merge pull request #15079 from gaye/bug-952719

Bug 952719 - Reenable notification click message reader test

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https://hg.mozilla.org/integration/gaia-central/rev/7d7a5621b6b3
Author: Gareth Aye <gaye@mozilla.com>
Desc: Bug 952719 - Reenable notification click message reader test