use decorator before export default may cause compilation problems

[linshuohao]

Version

2.7.8

Reproduction link

stackblitz.com

Steps to reproduce

After open the above reproduction, you will see the console shows the error: [vite] Internal server error: Cannot overwrite across a split point

What is expected?

rewriteDefault can transform

@Component
export default class App extends Vue {
  a = `;export xxx default`;
}

into

@Component
class App extends Vue {
  a = `;export xxx default`;
}
const ${as} = App

so that vite can work correctly

What is actually happening?

same as vuejs/core#6318