Delete a few unused local variables.

Change-Id: Ieed4fed91a4cbdf6ba2976536d55dab34b1b7ef2
Add a virtual destructor to JSObject.

No virtual destructor for polymorphic types is bad!

Change-Id: I1e014e52531a03edf2b9be9ecf1ccccc788ca01f
Avoid a few signed/unsigned comparison warnings.

Change-Id: I256d9b4e60ede409ba1471baf58a388b4f29f028
Enable -Wall and -Wextra for regsgen2.

Change-Id: I8b7dff8d6a4b760cb45667b24a3cb8470eb7a79e