lib: add Iterator global to primordials, improve iteration object coverage in frozen intrinsics

[Renegade334]

lib: add Iterator global to primordials

iterator_helpers is unflagged in V8 from v24.x.

lib: improve control abstraction coverage in frozen intrinsics

Adds the new internal iteration prototypes (%IteratorHelperPrototype%, %WrapForValidIteratorPrototype%) to frozen intrinsics, and improves/deduplicates coverage of iterator/generator objects.

Note that %AsyncFromSyncIteratorPrototype% is missing from the iterator spec – this is unresolvable AFAICT.

[bakkot]

Note that %AsyncFromSyncIteratorPrototype% is missing from the iterator spec – this is unresolvable AFAICT.

Indeed:

Async-from-Sync Iterator objects are never directly accessible to ECMAScript code.

It's a spec fiction used for defining behavior of other algorithms (for-await over a sync iterator, specifically), not a real thing (although engines might choose to have an internal representation of it for ease of implementation).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.35%. Comparing base (39b481b) to head (00e4207).
⚠️ Report is 23 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #63698      +/-   ##
==========================================
- Coverage   91.96%   90.35%   -1.61%     
==========================================
  Files         379      732     +353     
  Lines      166638   236691   +70053     
  Branches    25497    44583   +19086     
==========================================
+ Hits       153242   213867   +60625     
- Misses      13099    14563    +1464     
- Partials      297     8261    +7964     

Files with missing lines	Coverage Δ
lib/internal/freeze_intrinsics.js	97.05% <100.00%> (+0.08%)	⬆️
lib/internal/per_context/primordials.js	99.20% <100.00%> (+17.14%)	⬆️

... and 476 files with indirect coverage changes

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[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/73900/

[aduh95]

We might as well put them all into primordials since we're using them. wdyt about droping the repeating Prototype since this whole section is prototype-only as reminded by the comment you added?

Suggested change

	[
	{
	name: 'ArrayIteratorPrototype',
	original: Reflect.getPrototypeOf(Array.prototype[Symbol.iterator]()),
	},
	{
	name: 'AsyncIteratorPrototype',
	original: Reflect.getPrototypeOf(Reflect.getPrototypeOf(async function*() {}).prototype),
	},
	{
	name: 'StringIteratorPrototype',
	original: Reflect.getPrototypeOf(String.prototype[Symbol.iterator]()),
	},
	].forEach(({ name, original }) => {
	Object.entries({
	ArrayIterator: Reflect.getPrototypeOf(Array.prototype[Symbol.iterator]()),
	AsyncFunction: Reflect.getPrototypeOf(async function() {}),
	AsyncGeneratorFunction: Reflect.getPrototypeOf(async function*() {}),
	AsyncIterator: Reflect.getPrototypeOf(Reflect.getPrototypeOf(async function*() {}).prototype),
	GeneratorFunction: Reflect.getPrototypeOf(function*() {}),
	IteratorHelper: Reflect.getPrototypeOf(primordials.IteratorPrototypeDrop({ __proto__: null }, null)),
	MapIterator: Reflect.getPrototypeOf(new primordials.Map()[Symbol.iterator]()),
	// eslint-disable-next-line regexp/no-empty-group
	RegExpStringIterator: Reflect.getPrototypeOf(/(?:)/[Symbol.matchAll]()),
	SetIterator: Reflect.getPrototypeOf(new primordials.Set()[Symbol.iterator]()),
	StringIterator: Reflect.getPrototypeOf(String.prototype[Symbol.iterator]()),
	WrapForValidIterator: Reflect.getPrototypeOf(primordials.IteratorFrom({ __proto__: null })),
	}).forEach(({ 0: name, 1: original }) => {
	name += 'Prototype';

[aduh95]

If we take that suggestion, we should also avoid re-generating the uncurried next function for SafeMapIterator and SafeSetIterator

diff --git a/lib/internal/per_context/primordials.js b/lib/internal/per_context/primordials.js
index 6598db037e1..ec9e8c8af6d 100644
--- a/lib/internal/per_context/primordials.js
+++ b/lib/internal/per_context/primordials.js
@@ -379,10 +379,9 @@ const copyProps = (src, dest) => {
 /**
  * @type {typeof primordials.makeSafe}
  */
-const makeSafe = (unsafe, safe) => {
+const makeSafe = (unsafe, safe, next) => {
   if (SymbolIterator in unsafe.prototype) {
     const dummy = new unsafe();
-    let next; // We can reuse the same `next` method.
 
     ArrayPrototypeForEach(ReflectOwnKeys(unsafe.prototype), (key) => {
       if (!ReflectGetOwnPropertyDescriptor(safe.prototype, key)) {
@@ -419,6 +418,7 @@ primordials.makeSafe = makeSafe;
 primordials.SafeMap = makeSafe(
   Map,
   class SafeMap extends Map {},
+  primordials.MapIteratorPrototypeNext,
 );
 primordials.SafeWeakMap = makeSafe(
   WeakMap,
@@ -428,6 +428,7 @@ primordials.SafeWeakMap = makeSafe(
 primordials.SafeSet = makeSafe(
   Set,
   class SafeSet extends Set {},
+  primordials.SetIteratorPrototypeNext,
 );
 primordials.SafeWeakSet = makeSafe(
   WeakSet,