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

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https://hg.mozilla.org/integration/gaia-central/rev/b7c6efd07444
Author: Alive.Kuo <alegnadise@gmail.com>
Desc: Merge pull request #16061 from alivedise/bugzilla/935750/revive-dead-app-instead-destroy

Bug 935750 - Revive crashed app once got opened. r=etienne

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https://hg.mozilla.org/integration/gaia-central/rev/23ae61e91859
Author: Alive Kuo <alegnadise@gmail.com>
Desc: Bug 935750 - Implement Suspending AppWindow and Priority Manager

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "d544276be9ed2c125652fa0ffb19adae15af3434", 
+    "revision": "b7c6efd07444c2d0602bf734e618a9ace357be56", 
     "repo_path": "/integration/gaia-central"
 }