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

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https://hg.mozilla.org/integration/gaia-central/rev/79fdd326f7c0
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Merge pull request #13981 from pivanov/bug-939209

Bug 939209 - [Action Icons - Email] Remove shadows from action icons

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https://hg.mozilla.org/integration/gaia-central/rev/b978e893868a
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Bug 939209 - [Action Icons - Email] Remove shadows from action icons

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "da99b63fe2f21676c18aa5f3e20f52fed1d85ee7", 
+    "revision": "79fdd326f7c0cf9e7816bb72227ce4abbb77286e", 
     "repo_path": "/integration/gaia-central"
 }