[parser] Disallow Expression in for..of statements

test/mjsunit/for-in.js

Index: test/mjsunit/for-in.js
diff --git a/test/mjsunit/for-in.js b/test/mjsunit/for-in.js
index 644c27a63277b25729734afb061a286f38e1e801..9ee6461c128792b8920cce0e5626286012f7198e 100644
--- a/test/mjsunit/for-in.js
+++ b/test/mjsunit/for-in.js
@@ -131,3 +131,15 @@ for (i=0 ; i < 3; ++i) {
   }
   assertEquals(["2147483650"], keys);
 })();
+
+(function() {
+  var iterCount = 0;
+  var key;
+
+  for (key in { badKey: 0 }, { goodKey: 0 }) {
+    assertEquals('goodKey', key);
+    iterCount += 1;
+  }
+
+  assertEquals(1, iterCount);
+})();