Cache the flattened enumerable key snapshot for each `for..in` site and
reuse a `PropertyNameIterator` when the receiver shape, dictionary
generation, indexed storage kind and length, prototype chain
validity, and magical-length state still match.
Handle packed indexed receivers as well as plain named-property
objects. Teach `ObjectPropertyIteratorNext` in `asmint.asm` to return
cached property values directly and to fall back to the slow iterator
logic when any guard fails.
Treat arrays' hidden non-enumerable `length` property as a visited
name for for-in shadowing, and include the receiver's magical-length
state in the cache key so arrays and plain objects do not share
snapshots.
Add `test-js` and `test-js-bytecode` coverage for mixed numeric and
named keys, packed receiver transitions, re-entry, iterator reuse, GC
retention, array length shadowing, and same-site cache reuse.
The check_undeclared_exports() function only looked at top-level
VariableDeclaration nodes when collecting declared names. This missed
var declarations nested inside for loops, if/else blocks, try/catch,
switch statements, etc. Since var declarations are hoisted to the
enclosing module scope, they are valid export targets.
This caused legitimate modules (like the claude.ai JS bundle) to fail
with "'name' in export is not declared" errors when a var was declared
inside a for loop and later exported.
Fix this by recursively walking nested statements to collect var
declarations, while correctly not crossing function boundaries (since
var does not hoist out of functions) and not collecting block-scoped
let/const declarations.
For `export default (class Name { })`, two things were wrong:
The parser extracted the class expression's name as the export's
local binding name instead of `*default*`. Per the spec, this is
`export default AssignmentExpression ;` whose BoundNames is
`*default*`, not the class name.
The bytecode generator had a special case for ClassExpression that
skipped emitting InitializeLexicalBinding for named classes.
These two bugs compensated for each other (no crash, but wrong
behavior). Fix both: always use `*default*` as the local binding
name for expression exports, and always emit InitializeLexicalBinding
for the `*default*` binding.
