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

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https://hg.mozilla.org/integration/gaia-central/rev/a4970a36cbde
Author: autolander <bug.autolander@gmail.com>
Desc: Bug 1130883 - merge pull request #28246 from KevinGrandon:bug_1130883_history_heading_without_test to mozilla-b2g:master

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https://hg.mozilla.org/integration/gaia-central/rev/d271d7708836
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1130883 - Hide history heading when no results displayed r=daleharvey

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https://hg.mozilla.org/integration/gaia-central/rev/80882c383123
Author: autolander <bug.autolander@gmail.com>
Desc: Bug 1132996 - merge pull request #28272 from yzen:bug-1132996 to mozilla-b2g:master

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https://hg.mozilla.org/integration/gaia-central/rev/309411724630
Author: Yura Zenevich <yzenevich@mozilla.com>
Desc: Bug 1132996 - fixing the markup order based on presentation order.

b2g/config/gaia.json

@@ -1,9 +1,9 @@
 {
     "git": {
-        "git_revision": "a966e77a7cb8c703a8fb6f6d8ad659aca5b6512c", 
+        "git_revision": "1455349736277a498fa2fde57fbaddca63aab3b2", 
         "remote": "https://git.mozilla.org/releases/gaia.git", 
         "branch": ""
     }, 
-    "revision": "b811569e2c24e034183ec0811f9f684167ee3be4", 
+    "revision": "a4970a36cbdeb7792fd3a18781a2ba7234cf066f", 
     "repo_path": "integration/gaia-central"
 }