lib: make safe primordials safe to iterate

lib/internal/modules/cjs/loader.js

@@ -1269,7 +1269,7 @@ Module._preloadModules = function(requests) {
 };
 
 Module.syncBuiltinESMExports = function syncBuiltinESMExports() {
-  for (const mod of NativeModule.map.values()) {
+  for (const [, mod] of NativeModule.map) {
     if (mod.canBeRequiredByUsers) {
       mod.syncExports();
     }

lib/internal/per_context/primordials.js

@@ -75,6 +75,17 @@ function copyPrototype(src, dest, prefix) {
 function makeSafe(unsafe, safe) {
   copyProps(unsafe.prototype, safe.prototype);
   copyProps(unsafe, safe);
+  if (Symbol.iterator in unsafe.prototype) {
+    const createIterator = uncurryThis(unsafe.prototype[Symbol.iterator]);
+    const next = uncurryThis(
+      Reflect.getPrototypeOf(createIterator(new unsafe())).next
+    );
+    safe.prototype[Symbol.iterator] = function*() {
+      const iterator = createIterator(this);
+      let entry;
+      while (!(entry = next(iterator)).done) yield entry.value;
+    };
+  }
   Object.setPrototypeOf(safe.prototype, null);
   Object.freeze(safe.prototype);
   Object.freeze(safe);

lib/internal/source_map/source_map_cache.js

@@ -7,17 +7,12 @@ const {
   ObjectKeys,
   ObjectGetOwnPropertyDescriptor,
   ObjectPrototypeHasOwnProperty,
-  Map,
-  MapPrototypeEntries,
   RegExpPrototypeTest,
   SafeMap,
   StringPrototypeMatch,
   StringPrototypeSplit,
-  uncurryThis,
 } = primordials;
 
-const MapIteratorNext = uncurryThis(MapPrototypeEntries(new Map()).next);
-
 function ObjectGetValueSafe(obj, key) {
   const desc = ObjectGetOwnPropertyDescriptor(obj, key);
   return ObjectPrototypeHasOwnProperty(desc, 'value') ? desc.value : undefined;
@@ -195,11 +190,7 @@ function rekeySourceMap(cjsModuleInstance, newInstance) {
 function sourceMapCacheToObject() {
   const obj = ObjectCreate(null);
 
-  const it = MapPrototypeEntries(esmSourceMapCache);
-  let entry;
-  while (!(entry = MapIteratorNext(it)).done) {
-    const k = entry.value[0];
-    const v = entry.value[1];
+  for (const [k, v] of esmSourceMapCache) {
     obj[k] = v;
   }