Add some test runners.

Examples/test-suite/javascript/dynamic_cast_runme.js

@@ -0,0 +1,12 @@
+var dynamic_cast = require("./dynamic_cast");
+
+var f = new dynamic_cast.Foo();
+var b = new dynamic_cast.Bar();
+
+var x = f.blah();
+var y = b.blah();
+
+var a = dynamic_cast.do_test(y);
+if (a != "Bar::test") {
+  throw new Error("Failed.");
+}