function GradientStop(offset, rgbColor)
{
    this.offset = offset;
    this.rgbColor = rgbColor;
}
@class GradientStop
Stores gradient stop information.

@param offset   The offset of the gradient stop, in the range [0.0 to 1.0].
@param rgbColor The color of the gradient at this point, an \c #RGBColor object.

@return GradientStop object.