[strong] Implement static restrictions on binding 'undefined' in arrow functions

test/mjsunit/strong/undefined-arrow.js

+// Copyright 2014 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: --strong-mode --harmony-sloppy --harmony-arrow-functions
+"use strict";
+
+function CheckStrongMode(code) {
+  let strictContexts = [
+    ["'use strict';", ""],
+    ["function outer() { 'use strict';", "}"],
+    ["function outer() { 'use strict'; function inner() {", "}}"],
+    ["class C { m() {", "} }"]
+  ]
+  let strongContexts = [
+    ["'use strong';", ""],
+    ["function outer() { 'use strong';", "}"],
+    ["function outer() { 'use strong'; function inner() {", "}}"],
+    ["class C { m() { 'use strong';", "} }"]
+  ]
+
+  for (let context of strictContexts) {
+    assertDoesNotThrow(context[0] + code + context[1]);
+  }
+  for (let context of strongContexts) {
+    assertThrows(context[0] + code + context[1], SyntaxError);
+  }
+}
+
+CheckStrongMode("(undefined => {return});");
+assertThrows("(undefined => {'use strong';});");
+
+CheckStrongMode("((undefined, b, c) => {return});");
+assertThrows("((undefined, b, c) => {'use strong';});");
+
+CheckStrongMode("((a, undefined, c) => {return});");
+assertThrows("((a, undefined, c) => {'use strong';});");
+
+CheckStrongMode("((a, b, undefined) => {return})");
+assertThrows("((a, b, undefined) => {'use strong';});");