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

========

https://hg.mozilla.org/integration/gaia-central/rev/8dc29686ea31
Author: Wilson Page <wilsonpage@me.com>
Desc: Merge pull request #19693 from yor-mozilla-com/1011807

Bug 1011807 - Handle attribute change on gaia-header

========

https://hg.mozilla.org/integration/gaia-central/rev/47f1d0946fde
Author: Yan Or <yor@mozilla.com>
Desc: Bug 1011807 - Handle attribute change on gaia-header

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "6c7d7c523464de80214c548afb7da9b39fde9a4d", 
+    "revision": "8dc29686ea313c5aa95bd1803d0c8b243d490ee9", 
     "repo_path": "/integration/gaia-central"
 }