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

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https://hg.mozilla.org/integration/gaia-central/rev/1989e8286330
Author: autolander <bug.autolander@gmail.com>
Desc: Bug 1152772 - merge pull request #29508 from KevinGrandon:bug_1152772_downloaded_event_role to mozilla-b2g:master

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https://hg.mozilla.org/integration/gaia-central/rev/0749322a9213
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1152772 - [Search] Wait until downloadapplied to filter hidden roles

b2g/config/gaia.json

@@ -1,9 +1,9 @@
 {
     "git": {
-        "git_revision": "a99fe064f82834805ef0d3228f16203d0e7cc716", 
+        "git_revision": "dd876f167ad16070c412b1337b750c6c728af98e", 
         "remote": "https://git.mozilla.org/releases/gaia.git", 
         "branch": ""
     }, 
-    "revision": "0ecde425b576feb5ecf37ac02fdd7341e684b734", 
+    "revision": "1989e8286330b3f0075035e6b06e981225fbd71c", 
     "repo_path": "integration/gaia-central"
 }