Delegating yield does not re-box result objects

test/mjsunit/harmony/generators-iteration.js

Index: test/mjsunit/harmony/generators-iteration.js
diff --git a/test/mjsunit/harmony/generators-iteration.js b/test/mjsunit/harmony/generators-iteration.js
index 2ca35f2ee8a4037e86867fe4ecb49fa2eff0b9b6..dc210d5b1167521c833365e4a120ed8a6fc45439 100644
--- a/test/mjsunit/harmony/generators-iteration.js
+++ b/test/mjsunit/harmony/generators-iteration.js
@@ -346,6 +346,36 @@ TestGenerator(
     "foo",
     [3, undefined]);
 
+// Test that yield* re-yields received results without re-boxing.
+function TestDelegatingYield() {
+  function results(results) {
+    var i = 0;
+    function next() {
+      return results[i++];
+    }
+    return { next: next }
+  }
+  function* yield_results(expected) {
+    return yield* results(expected);
+  }
+  function collect_results(iter) {
+    var ret = [];
+    var result;
+    do {
+      result = iter.next();
+      ret.push(result);
+    } while (!result.done);
+    return ret;
+  }
+  // We have to put a full result for the end, because the return will re-box.
+  var expected = [{value: 1}, 13, "foo", {value: 34, done: true}];
+
+  // Sanity check.
+  assertEquals(expected, collect_results(results(expected)));
+  assertEquals(expected, collect_results(yield_results(expected)));
+}
+TestDelegatingYield();
+
 function TestTryCatch(instantiate) {
   function* g() { yield 1; try { yield 2; } catch (e) { yield e; } yield 3; }
   function Sentinel() {}