fix: add identifier for export default function without identifer

[underfin]

Description

The pr fixed some error with esm wrapped codegen and enable some esbuild passed test.

• add identifier for export default function without identifier
• avoid source mutation caused syntax error

export default class Foo {} Foo.prop = 123
// before
var Foo = class Foo {} Foo.prop = 123  // syntax error
// pr
var Foo = class Foo {}\n Foo.prop = 123 // add `\n` to avoid error

Test Plan

added.

---

[hyf0]

on hold for CR

[hyf0]

export default class Foo {} Foo.prop = 123
var Foo class Foo {}; Foo.prop = 123 // add `;` to avoid error

This looks confusing and invalid. What it means?

[underfin]

I updated at description

[hyf0]

@underfin Are export default class Foo being renamed to var Foo = class Foo expected? or just a temporary workaround?

[underfin]

Esbuild will codegen class Foo{} to var Foo = class {}, it is equals to var Foo = class Foo{}, so here not removed Foo.