Class instance property initializers + CreateDataPropertyOrThrow + computed property names

[bathos]

In V8 there are scenarios where it becomes observable that CreateDataPropertyOrThrow semantics are not really being used for instance field initializers. I've opened a Chromium issue.

Though the demonstration code uses return override, I suspect the issue can be illustrated just as readily by defining properties on this within initializer expressions themselves.

The attachment is not a proper test suite of the sort suitable for test262, but seeing which cases presently fail may still be instructive. All of the tests there succeed in Spidermonkey.

[bathos]

The issue here is narrower than I’d realized: per @joyeecheung, these failure cases occur only when using computed property syntax, and a minimal example demonstrating this was given in the Chromium bug thread:

class X {
 static ['name'] = "name"
}