Fix regression in default zoom setting

            // Remember the current zoom density before it gets changed.

            final float originalDefault = mDefaultScale;

            // set the new default density

            mDisplayDensity = density;

            setDefaultZoomScale(density);

            float scaleChange = (originalDefault > 0.0) ? density / originalDefault: 1.0f;

            // adjust the scale if it falls outside the new zoom bounds