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

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https://hg.mozilla.org/integration/gaia-central/rev/a578eeda5da5
Author: autolander <bug.autolander@gmail.com>
Desc: Bug 1147316 - merge pull request #30108 from Cwiiis:bug1147316-fix-cutoff-collection-icon to mozilla-b2g:master

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https://hg.mozilla.org/integration/gaia-central/rev/e448260bf8c8
Author: Chris Lord <chrislord.net@gmail.com>
Desc: Bug 1147316 - Fix cut-off add-to-collection icon. r=kgrandon

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https://hg.mozilla.org/integration/gaia-central/rev/dca47d6d0c8a
Author: autolander <bug.autolander@gmail.com>
Desc: Bug 1162732 - merge pull request #30065 from gabrielesvelto:bug-1162732-speaker-and-mute-button-status to mozilla-b2g:master

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https://hg.mozilla.org/integration/gaia-central/rev/22b160cac63e
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Bug 1162732 - Properly adjust the speaker and mute buttons depending on the call state r=thills

b2g/config/gaia.json

@@ -1,9 +1,9 @@
 {
     "git": {
-        "git_revision": "dad6a35a8c927a029f7cd3eac2397e256e155808", 
+        "git_revision": "a1c099f167d778908bc45d0e1f834f5ccf97f0ba", 
         "remote": "https://git.mozilla.org/releases/gaia.git", 
         "branch": ""
     }, 
-    "revision": "1a9b9a894cb331ff05b49ab6f764fabcd39b3e8a", 
+    "revision": "a578eeda5da58b4fb573d1acd2dcef7e189e4b1c", 
     "repo_path": "integration/gaia-central"
 }