Add new variant needle for KDE Firefox addon install

Looks like font rendering changed a tad in Rawhide.

needles/firefox/addon_install-kde-20170710.json

@@ -0,0 +1,22 @@
+{
+  "properties": [],
+  "area": [
+    {
+      "xpos": 60,
+      "height": 33,
+      "type": "match",
+      "ypos": 107,
+      "width": 34
+    },
+    {
+      "type": "match",
+      "width": 44,
+      "ypos": 231,
+      "xpos": 358,
+      "height": 17
+    }
+  ],
+  "tags": [
+    "firefox_addon_install"
+  ]
+}