Update KDE 'addon install' Firefox needle

This looks different in KDE to GNOME for some reason, so we need
yet another new needle.

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

needles/firefox/addon_install-kde-20190325.json

@@ -0,0 +1,22 @@
+{
+  "area": [
+    {
+      "height": 35,
+      "type": "match",
+      "ypos": 110,
+      "width": 35,
+      "xpos": 241
+    },
+    {
+      "ypos": 257,
+      "width": 26,
+      "xpos": 517,
+      "height": 14,
+      "type": "match"
+    }
+  ],
+  "properties": [],
+  "tags": [
+    "firefox_addon_install"
+  ]
+}