Bug 1240997 - Enable 3 Bluetooth marionette tests on B2G emulator-kk, r=btian

1. [test_dom_BluetoothManager.js]
2. [test_dom_BluetoothAdapter_enable.js]
3. [test_dom_BluetoothAdapter_setters.js]

dom/bluetooth/tests/marionette/manifest.ini

@@ -7,14 +7,11 @@ qemu = false
 # we want to disable.
 
 [test_dom_BluetoothManager.js]
-disabled = Bug 1175389
-
+skip-if = android_version < '19'
 [test_dom_BluetoothAdapter_enable.js]
-disabled = Bug 1175389
-
+skip-if = android_version < '19'
 [test_dom_BluetoothAdapter_setters.js]
-disabled = Bug 1175389
-
+skip-if = android_version < '19'
 [test_dom_BluetoothDevice.js]
 disabled = Bug 1175389