pub fn new_inherited(height: u64, width: u64, placeholder: Option<&HTMLCanvasElement>) -> OffscreenCanvas {
        OffscreenCanvas {
            reflector_: Reflector::new(),
            height: height,
            width: width,
            context: DomRefCell::new(None),
            placeholder: placeholder,
        }
    }

    pub fn new(global: &GlobalScope, height: u64, width: u64, placeholder: Option<&HTMLCanvasElement>) -> DomRoot<OffscreenCanvas> {
        reflect_dom_object(Box::OffscreenCanvas::new_inherited(), global, OffscreenCanvas::Bindings::Wrap)
    }

    pub fn Constructor (global: &GlobalScope, height: u64, width: u64) -> Fallible<DomRoot<OffscreenCanvas>> {
        //step 1
        let offscreencanvas = OffscreenCanvas::new(global,height,width);
        //step 2

        if(offscreencanvas.context.is_some()){
            return Err(Error::InvalidState);
        }

        //offscreencanvas.height = height;
        //offscreencanvas.width = width;

        if(offscreencanvas.placeholder.is_null()) {
            offscreencanvas.placeholder = ptr::null();
        }
        else {
            //offscreencanvas.placeholder = &self.placeholder;
        }

        //step 3
        Ok(offscreencanvas);
    }

}