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

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https://hg.mozilla.org/integration/gaia-central/rev/d818ea3ebb2a
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Merge pull request #15891 from davidflanagan/revert959049

Revert "Merge pull request #15702 from davidflanagan/bug959049"

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https://hg.mozilla.org/integration/gaia-central/rev/118237d38edb
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Revert "Merge pull request #15702 from davidflanagan/bug959049"

This reverts commit cfeb5bf7e7665e4be412d1f774bd46fadeff3c93, reversing
changes made to a9a4e7bbcf55d1bd0a0d441f7dcc6271cc2dc6b1.

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "7ecc490551fec30f53b0770bcec9c597e3e426bf", 
+    "revision": "d818ea3ebb2a3500a772cda2c0811c299b862682", 
     "repo_path": "/integration/gaia-central"
 }