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

test/mjsunit/strong/literals.js

Index: test/mjsunit/strong/literals.js
diff --git a/test/mjsunit/strong/literals.js b/test/mjsunit/strong/literals.js
index 8c04d6e35a7f7ed2fd48a30052d92b5e145cf96a..28123c218ee1d7675f36164758378d7c25940c7c 100644
--- a/test/mjsunit/strong/literals.js
+++ b/test/mjsunit/strong/literals.js
@@ -112,14 +112,14 @@
   assertWeakArray({a: [], b: {}}.a);
 })();
 
-(function StrongArrayLiterals(...args) {
+(function StrongArrayLiterals() {
   'use strong';
   function assertStrongArray(x) {
     assertTrue(%IsStrong(x));
     assertSame(Array.prototype, Object.getPrototypeOf(x));
   }
   let [...r] = [];
-  assertStrongArray(args);
+  assertStrongArray((function(...a) { return a; })());
   assertStrongArray(r);
   assertStrongArray([]);
   assertStrongArray([1, 2, 3]);