add 90px icon (for 1.5x pixel-ratio displays) (bug 898382)

Author: cvan

yulelog/90.png

@@ -13,6 +13,7 @@
     },
     "icons": {
         "60": "/60.png",
+        "90": "/90.png",
         "128": "/128.png"
     },
     "launch_path": "/index.html",