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

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https://hg.mozilla.org/integration/gaia-central/rev/9d18e3a87022
Author: autolander <bug.autolander@gmail.com>
Desc: Bug 1135023 - merge pull request #28465 from gabrielesvelto:bug-1135023-contact-cache-validation to mozilla-b2g:master

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https://hg.mozilla.org/integration/gaia-central/rev/457436f7b05f
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Bug 1135023 - Add missing `self` declarations in the call log database r=thills

b2g/config/gaia.json

@@ -1,9 +1,9 @@
 {
     "git": {
-        "git_revision": "edfd00a204e04d4ba90df3a1ae29dcdf7f54049b", 
+        "git_revision": "7ba096b4aa9bfb5d0b663e47e9d6b4b696d1180c", 
         "remote": "https://git.mozilla.org/releases/gaia.git", 
         "branch": ""
     }, 
-    "revision": "2573ff40f5d52ca3611bfbb915ea954c7928923b", 
+    "revision": "9d18e3a870220fee847dc3b181e4eff37bf4733c", 
     "repo_path": "integration/gaia-central"
 }