bool
WebGLFramebuffer::Attachment::HasSameDimensionsAs(const Attachment& other) const {
    const WebGLRectangleObject *thisRect = RectangleObject();
    const WebGLRectangleObject *otherRect = other.RectangleObject();
    return thisRect &&
           otherRect &&
           thisRect->HasSameDimensionsAs(*otherRect);
}