[parser] disallow language mode directive in body of function with non-simple parameters

test/mjsunit/harmony/arrow-rest-params.js

Index: test/mjsunit/harmony/arrow-rest-params.js
diff --git a/test/mjsunit/harmony/arrow-rest-params.js b/test/mjsunit/harmony/arrow-rest-params.js
index b1e8dcc1b99b484a9257b1f3a4c73ad5c94db0e1..0ee77390ed21496f590de890686891c29e7c3f96 100644
--- a/test/mjsunit/harmony/arrow-rest-params.js
+++ b/test/mjsunit/harmony/arrow-rest-params.js
@@ -18,18 +18,20 @@
 //
 //   strictTest(6,5,4,3,2,1)
 //
-var strictTest = (a, b, ...c) => {
+var strictTest = (() => {
   "use strict";
-  assertEquals(Array, c.constructor);
-  assertTrue(Array.isArray(c));
+  return (a, b, ...c) => {
+    assertEquals(Array, c.constructor);
+    assertTrue(Array.isArray(c));
 
-  var expectedLength = (a === undefined) ? 0 : a - 2;
-  assertEquals(expectedLength, c.length);
+    var expectedLength = (a === undefined) ? 0 : a - 2;
+    assertEquals(expectedLength, c.length);
 
-  for (var i = 2; i < a; ++i) {
-    assertEquals(c[i - 2], a - i);
-  }
-}
+    for (var i = 2; i < a; ++i) {
+      assertEquals(c[i - 2], a - i);
+    }
+  };
+})();
 
 var sloppyTest = (a, b, ...c) => {
   assertEquals(Array, c.constructor);