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

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https://hg.mozilla.org/integration/gaia-central/rev/270dd5504023
Author: Rudy Lu <me@rudy.lu>
Desc: Merge pull request #18367 from RudyLu/keyboard/Bug993952-squash

Bug 993952 - Position inactive keyboards off screen instead of display: ...
r=rudylu

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https://hg.mozilla.org/integration/gaia-central/rev/ef02adbe8911
Author: Jan Jongboom <janjongboom@gmail.com>
Desc: Bug 993952 - Position inactive keyboards off screen instead of display: none
 - Move panels fully out of viewport

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https://hg.mozilla.org/integration/gaia-central/rev/f47d9872c964
Author: Anthony Ricaud <anthony@ricaud.me>
Desc: Merge pull request #18258 from Rik/remove-non-promise-995630

Bug 995630 - Remove Gaia code that supported the old mozTelephony.dial/d... r=etienne

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https://hg.mozilla.org/integration/gaia-central/rev/435ac498602b
Author: Anthony Ricaud <anthony@ricaud.me>
Desc: Bug 995630 - Remove Gaia code that supported the old mozTelephony.dial/dialEmergency API

- Removed requireApp usage
- Moved the telephony.dial/dialEmergency stubbing to the main suite
- Some modifications for jshint compat

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "f42e47a5c154b017d75e309cf83cf15551b8d1ca", 
+    "revision": "270dd5504023c3bd9099035bec0ad494e166dd9f", 
     "repo_path": "/integration/gaia-central"
 }