add firefox extension template

externs/webextension_polyfill/captiveportal/Static.hx

@@ -0,0 +1,26 @@
+package webextension_polyfill.captiveportal;
+
+typedef Static = {
+	/**
+		Returns the current portal state, one of `unknown`, `not_captive`, `unlocked_portal`, `locked_portal`.
+	**/
+	function getState():Void;
+	/**
+		Returns the time difference between NOW and the last time a request was completed in milliseconds.
+	**/
+	function getLastChecked():Void;
+	/**
+		Fired when the captive portal state changes.
+	**/
+	var onStateChanged : webextension_polyfill.events.Event<(details:OnStateChangedDetailsType) -> Void>;
+	/**
+		This notification will be emitted when the captive portal service has determined that we can connect to the internet.
+		The service will pass either `captive` if there is an unlocked captive portal present,
+		or `clear` if no captive portal was detected.
+	**/
+	var onConnectivityAvailable : webextension_polyfill.events.Event<(status:OnConnectivityAvailableStatusEnum) -> Void>;
+	/**
+		Return the canonical captive-portal detection URL. Read-only.
+	**/
+	var canonicalURL : webextension_polyfill.types.Setting;
+};