Generate class ref ID for anonymous class only

[JLHwung]

Q	A
Fixed Issues?	Fixes #11990
Patch: Bug Fix?	Y
Tests Added + Pass?	Yes
License	MIT

A named class expression can be referenced in the field initializers, e.g.

const x = class B {
  static b = B.name
}

before this PR we generated _class reference to B but did not replace B.name to _class.name.

const x = (_temp = _class = class B {}, _defineProperty(_class, "b", B.name), _temp);

I assume that we are safe to produce (X = class X {}) as the following cases are invalid

(a) => { a = 1; return class a {} };
const a = class a {};

so this PR clones the class binding identifier when it exists, since it could be referenced in field initializers.

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[nicolo-ribaudo]

I assume that we are safe to produce (X = class X {}) as the following cases are invalid

(a) => { a = 1; return class a {} };
const a = class a {};

Are you sure? I think both are valid (at least, they work in Chrome)

[JLHwung]

@nicolo-ribaudo Ah I probably mess up a bit in the devtools. Closing this as this approach will introduce new issues.