Normative: Do not capture the script/module in new Function and indirect eval

[nicolo-ribaudo]

We have three ways of dynamically executing code:

• direct eval
• indirect eval
• new Function&friends

The main difference is that direct eval has some magic behavior, capturing the context where it's being called, while indirect eval and new Function are supposed to be "normal functions" that do not perform any dynamic scoping.

There is however a case where indirect eval and new Function are affected by where they are being called: they propagate the active script or module.

This pull request changes them to instead run their code with a null ScriptOrModule, similarly to code run in HTML event handlers. This ensures that the behavior of indirect eval and new Function does not depend on where they are called. The observable change is that in (eval, 0)("import('./foo')"), ./foo is resolved relative to the base URL of the Realm and not of the script or module calling eval (and same for new Function).

I believe that this PR can be web compatible because there is currently different behaviors across different browsers (see #3160 for more details).

Fixes #3160.

[devsnek]

i don't think this can be null (or appear to be null in the case of ~hidden~?). See for example #1670.

and so this leads me to my question, why not just create a new script record for indirect evaluators?

[nicolo-ribaudo]

It can be null when you define a function inside an inline event handler in HTML, since in that case GetActiveScriptOrModule() is null.

and so this leads me to my question, why not just create a new script record for indirect evaluators?

That would work too, but we probably need a new host hook to let hosts define the [[HostDefined]] slot of those new script records created within ECMA-262.

[devsnek]

I guess another perspective is that the ecmascript code being evaluated is not technically from a Script or a Module. Though it would seem to clean up the existence of HideParentScriptOrModule if we set something there explicitly.

[devsnek]

Could this be unchanged and propagate ~hidden~ up to GetActiveScriptOrModule, which could turn it into null?

[linusg]

Suggested change

	A Boolean indicating wether, when looking for an execution context with a non-*null* ScriptOrModule component, this execution context should allow looking at its ancestors or not. If not explicitly set, defaults to *false*.
	A Boolean indicating whether, when looking for an execution context with a non-*null* ScriptOrModule component, this execution context should allow looking at its ancestors or not. If not explicitly set, defaults to *false*.