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

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https://hg.mozilla.org/integration/gaia-central/rev/7270b35c7a74
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Bug 939229 - [Action Icons - Gallery] Remove shadows from action icons

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "a81626341046f2426526effc44f048599150b8a4", 
+    "revision": "7270b35c7a74968de7e479be0f73716326c7f1bc", 
     "repo_path": "/integration/gaia-central"
 }