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

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https://hg.mozilla.org/integration/gaia-central/rev/beb10c663985
Author: Martijn <martijn.martijn@gmail.com>
Desc: Merge pull request #30204 from mwargers/1157316

Bug 1157316 - test_lockscreen_time_check.py:  JavascriptException

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https://hg.mozilla.org/integration/gaia-central/rev/49d2ba473da2
Author: Martijn Wargers <mwargers@mozilla.com>
Desc: Bug 1157316 - test_lockscreen_time_check.py:  JavascriptException

b2g/config/gaia.json

@@ -1,9 +1,9 @@
 {
     "git": {
-        "git_revision": "91a9887f2768b4ebd9a30f8651a387a7ea41c96b", 
+        "git_revision": "4bcd260ae62f2d40db8523f92cf7590b91d09465", 
         "remote": "https://git.mozilla.org/releases/gaia.git", 
         "branch": ""
     }, 
-    "revision": "91805a7dc452d2379bbded87b684aafa4d4f7b3a", 
+    "revision": "beb10c6639853af1842bc2017257b07e6695863d", 
     "repo_path": "integration/gaia-central"
 }