code: @Override
      public boolean hasInstance(Scriptable instance)
      {
          Object protoProp = ScriptableObject.getProperty(this, "prototype");
          if (protoProp instanceof Scriptable) {
              return ScriptRuntime.jsDelegatesTo(instance, (Scriptable)protoProp);
          }
          throw ScriptRuntime.typeError1("msg.instanceof.bad.prototype",
                                         getFunctionName());
      }
docs: Implements the instanceof operator for JavaScript Function objects.
  <p>
  <code>
  foo = new Foo();<br>
  foo instanceof Foo;  // true<br>
  </code>
  
  @param instance The value that appeared on the LHS of the instanceof
  operator
  @return true if the "prototype" property of "this" appears in
  value's prototype chain