Bumping gaia.json for 4 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/e4822b34a357
Author: tamarahills <thills@mozilla.com>
Desc: Merge pull request #25909 from tamarahills/bugfix/1078448

Bug 1078448 - Modify call_screen_window.js reloadWindow to not leak Call...

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https://hg.mozilla.org/integration/gaia-central/rev/a15b584927c9
Author: Tamara Hills <thills@mozilla.com>
Desc: Bug 1078448 - Modify call_screen_window.js reloadWindow to not leak CallScreen app instances. r=drs.

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https://hg.mozilla.org/integration/gaia-central/rev/38844206ba88
Author: Florin Strugariu <florin.strugariu@softvision.ro>
Desc: Merge pull request #26447 from davehunt/bug1074117-gallery

Bug 1074117 - Use expected conditions and optimise element lookups in gallery app object

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https://hg.mozilla.org/integration/gaia-central/rev/8ee272531ef9
Author: Dave Hunt <dave.hunt@gmail.com>
Desc: Bug 1074117 - Use expected conditions and optimise element lookups in email app object. r=fstrugariu

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "b710813303f93261bc38283142d4c4ca9fe35b41", 
+    "revision": "e4822b34a3571fabf58b7769230b12452fbba73d", 
     "repo_path": "integration/gaia-central"
 }