toMarker(workspace) {
    const marker = new Blockly.Marker();
    const node = this.createNode(workspace);
    marker.setCurNode(node);
    return marker;
  }
Create a Marker at the Position.
@param {!Blockly.Workspace} workspace The workspace the user is on.
@returns {!Blockly.Marker} A Marker with the curNode set to the Position.
@public