Shrink KDE Firefox launcher icon to avoid background issues

Existing one doesn't match if the background is too different,
shrink it to just the center of the icon.

Signed-off-by: Adam Williamson <awilliam@redhat.com>

needles/firefox/launcher-kde-20180604.json

@@ -1,16 +1,16 @@
 {
+    "area": [
+        {
+            "height": 21,
+            "type": "match",
+            "width": 21,
+            "xpos": 51,
+            "ypos": 214
+        }
+    ],
     "properties": [],
     "tags": [
         "browser_launcher",
         "firefox_launcher"
-  ],
-  "area": [
-    {
-      "height": 31,
-      "xpos": 46,
-      "ypos": 209,
-      "width": 31,
-      "type": "match"
-    }
     ]
 }