Bumping gaia.json for 2 gaia-central revision(s)

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https://hg.mozilla.org/integration/gaia-central/rev/66da5a7070f6
Author: Ian Liu <iliu@mozilla.com>
Desc: Merge pull request #11145 from ian-liu/clock/Bug896931_Clock_app_need_1.5x_ratio_pictures_for_hd_versions

Bug 896931 - [Clock][UX][HD] Clock app need 1.5x ratio pictures for hd versions, r=@rexboy7

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https://hg.mozilla.org/integration/gaia-central/rev/c11c5464f253
Author: ian-liu <iliu@mozilla.com>
Desc: Bug 896931 - [Clock][UX][HD] Clock app need 1.5x ratio pictures for hd versions

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "089e712b0ed6ce9bc3009b854e4e5af458914909", 
+    "revision": "66da5a7070f6af7dd79e8a40290618dd0e2f3a43", 
     "repo_path": "/integration/gaia-central"
 }