code: function _Browser_getViewportOf(id) {
      return _Browser_withNode(id, function(node) {
        return {
          scene: {
            width: node.scrollWidth,
            height: node.scrollHeight
          },
          viewport: {
            x: node.scrollLeft,
            y: node.scrollTop,
            width: node.clientWidth,
            height: node.clientHeight
          }
        };
      });
    }
docs: ELEMENT VIEWPORT