Ensure IteratorClose is called for errors in non-declaring assignments

test/mjsunit/harmony/iterator-close.js

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Flags: --harmony-iterator-close
 
 function* g() { yield 42; return 88 };
 
 
 // Return method is "undefined".
@@ skipping 137 matching lines @@
   })());
   assertEquals([[]], log);
 
   log = [];
   assertEquals(42, eval('for (let x of g()) { x; }'));
   assertEquals([], log);
 
   log = [];
   assertEquals(42, eval('for (x of g()) { x; }'));
   assertEquals([], log);
+
+  // Even if doing the assignment throws, still call return
+  x = { set attr(_) { throw 1234; } };
+  assertThrowsEquals(() => {
+    for (x.attr of g()) { throw 456; }
+  }, 1234);
+  assertEquals([[]], log);
 }
 
 
 // Return method throws.
 {
   let log = [];
   g.prototype.return = (...args) => { log.push(args); throw 23 };
 
   log = [];
   assertThrowsEquals(() => {
@@ skipping 189 matching lines @@
     for (let x of g1()) {
       try {
         for (let y of g2()) {
         }
       } catch (_) {}
       if (x == 2) break;
     }
   }, 5);
   assertEquals([1], log);
 }