Swap out booleans in ancestors map with ints

This converts the myriad of `!0`s in the optimized code with `1`s, saving about 4kb on `reversi.js`. `ancestors` is only every used in `ClassTypeData`, and there its usages are wrapped in `!!()` so the fact that it's an int instead of a boolean is immaterial.

Not a huge reduction, but a penny saved...