8176501: Method Shape.getBounds2D() incorrectly includes Bezier control points in bounding box

Restore the "final" and "synchronized" modifiers for this method. I don't think these were removed on purpose; the intent behind this PR is not related to the modifiers of the method.

This is in response to prrace's code review comment:

> So no longer final, and no longer synchronized.
> This means a CSR is required and we need to think about it .. the
> intention was that the subclass not over-ride.
> And why remove synchronized ? I am fairly sure it was there to make
> sure no one was mutating the Path whilst bounds are being calculated.
> And you are using getPathIterator(AffineTransform) and the docs for
> that say it isn't thread safe.
> So I think this implementation needs to be thought about very carefully.

https://github.com/openjdk/jdk/pull/6227#issuecomment-995305817