Bumping gaia.json for 2 gaia-central revision(s)

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https://hg.mozilla.org/integration/gaia-central/rev/c8bffe868520
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Merge pull request #10352 from davidflanagan/bug882197

Bug 882197: remember cursor position after calling replaceSurroundingText r=dhylands

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https://hg.mozilla.org/integration/gaia-central/rev/19cdfadf93a9
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Bug 882197: remember cursor position after calling replaceSurroundingText

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "e0863efffa89fe7b8dfdfb9530ac1f0a6b1736d6", 
+    "revision": "c8bffe868520d2136080002f314aedd1841d0220", 
     "repo_path": "/integration/gaia-central"
 }