Fix behavior of return on yield*.

test/mjsunit/harmony/generators-turbo.js

Index: test/mjsunit/harmony/generators-turbo.js
diff --git a/test/mjsunit/harmony/generators-turbo.js b/test/mjsunit/harmony/generators-turbo.js
index d12c8cffe1aae50ef5830aafe585d88d257d7ae5..23913e4229a227b58be0fd63d262413c33c7a53b 100644
--- a/test/mjsunit/harmony/generators-turbo.js
+++ b/test/mjsunit/harmony/generators-turbo.js
@@ -643,3 +643,13 @@ function Throw(generator, ...args) {
   assertEquals({value: 42, done: false}, Next(g));
   assertEquals({value: 42, done: false}, Next(g));
 }
+
+{
+  let foo = function*() {
+    yield* (function*() { yield 42; }());
+    assertUnreachable();
+  }
+  g = foo();
+  assertEquals({value: 42, done: false}, Next(g));
+  assertEquals({value: 23, done: true}, Return(g, 23));
+}