Per the TC39 `ResolveExport` spec, when a star-reexported module
re-exports a name back to the importer cyclically, cycle detection
should return null from the cyclic branch and the star loop should
fall through to a non-cyclic source. In the new test262 cases:

  // a.js
  export * from './b.js';
  export * from './c.js';
  // b.js
  export { foo } from './a.js';
  // c.js
  export let foo = 42;

webpack previously hoisted every star-exported name into the
importer's namespace without per-name cycle detection, so b's cyclic
`foo` won over c's terminal binding. The generated bundle emitted

  a.foo = () => b.foo
  b.foo = () => a.foo

— a getter chain that recurses forever and throws "Maximum call
stack size exceeded" at runtime.

`HarmonyExportImportedSpecifierDependency` now detects when a
candidate star-export contribution's target chain loops back to the
importer under the same name and skips it. The check runs in both
`determineExportAssignments` (which builds the combined name set
for star reexports) and `getStarReexports` (which decides per-dep
contributions), walking the target chain one hop at a time with
visited tracking so namespace targets (`export * as ns from ...`)
and unrelated cycles don't trigger the latent infinite-loop in
`ExportsInfo._findTarget`.

The two test262 cases `instn-star-iee-single-cycle-same-name` and
`instn-star-iee-multi-cycle-same-name` now pass instead of throwing
at runtime.

The cycle detector in HarmonyExportImportedSpecifierDependency is called
for every export of every star-reexported module. In barrel-style code
(e.g. `export * from './depN.js'` repeated thousands of times, as in
the `side-effects-reexport` benchmark) this path is hot enough that
allocations and redundant work add a few percent to compile time.

Two small fixes:

- Probe the first chain hop before allocating the `visited` Set. For
  terminal local bindings (no `_target`) we now return immediately
  after one `findTarget` call without allocating the Set; only multi-hop
  chains pay for cycle tracking.
- Hoist the `() => true` filter into a module-level `RETURNS_TRUE`
  constant so each call doesn't allocate a fresh closure.
- In `getStarReexports`, check `hiddenExports` (a cheap `Set.has`)
  before running the cycle walk. Names that an earlier non-cyclic star
  already provided are guaranteed non-cyclic because
  `determineExportAssignments` excludes cyclic candidates from
  `hiddenExports` upstream.