[cleanup] Mark unused files

test/swftests.unused/StringConversion.as

@@ -0,0 +1,11 @@
+// input: []
+// output: 2
+
+package {
+public class StringConversion {
+    public static function main():int{
+        var s:String = String(99);
+        return s.length;
+    }
+}
+}