babel/packages/babel-plugin-transform-es2015-object-super/src/index.js

import ReplaceSupers from "babel-helper-replace-supers";

function replacePropertySuper(path, node, scope, getObjectRef, file) {
  const replaceSupers = new ReplaceSupers({
    getObjectRef: getObjectRef,
    methodNode: node,
    methodPath: path,
    isStatic: true,
    scope: scope,
    file: file,
  });

  replaceSupers.replace();
}

export default function ({ types: t }) {
  return {
    visitor: {
      ObjectExpression(path, state) {
        let objectRef;
        const getObjectRef = () => objectRef = objectRef || path.scope.generateUidIdentifier("obj");

        path.get("properties").forEach((propertyPath) => {
          if (!propertyPath.isMethod()) return;

          const propPaths: Array = path.get("properties");
          for (let propPath of propPaths) {
            if (propPath.isObjectProperty()) propPath = propPath.get("value");
            replacePropertySuper(propPath, propPath.node, path.scope, getObjectRef, state);
          }
        });

        if (objectRef) {
          path.scope.push({ id: objectRef });
          path.replaceWith(t.assignmentExpression("=", objectRef, path.node));
        }
      },
    },
  };
}