[parser] Fix bug in for-of desugaring.

test/mjsunit/es6/iterator-close.js

Index: test/mjsunit/es6/iterator-close.js
diff --git a/test/mjsunit/es6/iterator-close.js b/test/mjsunit/es6/iterator-close.js
index 1a96bee22323162b652108fa433775a538ad6e24..fd8f361e5e93978031589dc50e19b895ad721948 100644
--- a/test/mjsunit/es6/iterator-close.js
+++ b/test/mjsunit/es6/iterator-close.js
@@ -966,8 +966,9 @@ function* g() { yield 42; return 88 };
 
 // Next method throws.
 {
+  let closed = false;
   g.prototype.next = () => { throw 666; };
-  g.prototype.return = () => { assertUnreachable() };
+  g.prototype.return = () => { closed = true; };
 
 
   assertThrowsEquals(() => {
@@ -1025,13 +1026,17 @@ function* g() { yield 42; return 88 };
   assertThrowsEquals(() => {
     (([...x]) => x)(g());
   }, 666);
+
+
+  assertFalse(closed);
 }
 
 
 // Value throws.
 {
+  let closed = false;
   g.prototype.next = () => ({get value() {throw 666}});
-  g.prototype.return = () => { assertUnreachable() };
+  g.prototype.return = () => { closed = true; };
 
 
   assertThrowsEquals(() => {
@@ -1089,13 +1094,17 @@ function* g() { yield 42; return 88 };
   assertThrowsEquals(() => {
     (([...x]) => x)(g());
   }, 666);
+
+
+  assertFalse(closed);
 }
 
 
 // Done throws.
 {
+  let closed = false;
   g.prototype.next = () => ({get done() {throw 666}});
-  g.prototype.return = () => { assertUnreachable() };
+  g.prototype.return = () => { closed = true; };
 
 
   assertThrowsEquals(() => {
@@ -1153,6 +1162,9 @@ function* g() { yield 42; return 88 };
   assertThrowsEquals(() => {
     (([...x]) => x)(g());
   }, 666);
+
+
+  assertFalse(closed);
 }