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

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https://hg.mozilla.org/integration/gaia-central/rev/c9704b92fb86
Author: steveck-chung <schung@mozilla.com>
Desc: Merge pull request #20073 from pacorampas/placeholder-message-1016541

Bug 1016541 - Thread and Composer. The input placeholder text (Message) should be italic. r=schung

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https://hg.mozilla.org/integration/gaia-central/rev/f0920b816224
Author: Paco Rampas <pacorampas@gmail.com>
Desc: Bug 1016541 - Thread and Composer. The input placeholder text (Message) should be italic
Bumping manifests a=b2g-bump