add firefox extension template

externs/ts/AnyOf2.hx

@@ -0,0 +1,11 @@
+package ts;
+
+/**
+	AnyOf implementation generated by dts2hx
+**/
+@:transitive extern abstract AnyOf2<T0, T1>(Dynamic) from T0 from T1 to T0 to T1 {
+	var asType0(get, never) : T0;
+	private inline function get_asType0():T0 return this;
+	var asType1(get, never) : T1;
+	private inline function get_asType1():T1 return this;
+}