fixed a reference in a test

tests/cases/fourslash/addDeclareToFunction.ts

@@ -1,7 +1,8 @@
+/// <reference path="fourslash.ts" />
+
 //// /*1*/function parseInt(s/*2*/:string):number;
 
 goTo.marker('2');
 edit.deleteAtCaret(':string'.length);
 goTo.marker('1');
-edit.insert('declare ');
-
+edit.insert('declare ');