ES6: Update unscopables to match spec

test/mjsunit/es6/unscopables.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.
 
 var global = this;
 var globalProto = Object.getPrototypeOf(global);
 
 // Number of objects being tested. There is an assert ensuring this is correct.
 var objectCount = 21;
 
@@ skipping 125 matching lines @@
     assertEquals(5, y);
     assertEquals(3, z);
   }
 
   object[Symbol.unscopables] = {x: 0, y: true};
   with (object) {
     assertEquals(1, x);
     assertEquals(2, y);
     assertEquals(3, z);
   }
+
+  object[Symbol.unscopables] = {x: 0, y: undefined};
+  with (object) {
+    assertEquals(1, x);
+    assertEquals(5, y);
+    assertEquals(3, z);
+  }
 }
 runTest(TestBasics);
 
 
 function TestUnscopableChain(object) {
   var x = 1;
   object.x = 2;
 
   with (object) {
     assertEquals(2, x);
   }
 
   object[Symbol.unscopables] = {
     __proto__: {x: true}
   };
   with (object) {
     assertEquals(1, x);
   }
+
+  object[Symbol.unscopables] = {
+    __proto__: {x: undefined}
+  };
+  with (object) {
+    assertEquals(2, x);
+  }
 }
 runTest(TestUnscopableChain);
 
 
 function TestBasicsSet(object) {
   var x = 1;
   object.x = 2;
 
   with (object) {
     assertEquals(2, x);
@@ skipping 41 matching lines @@
     assertEquals(3, z);
   }
 
   proto[Symbol.unscopables] = {y: true};
   object[Symbol.unscopables] = {x: true};
   with (object) {
     assertEquals(1, x);
     assertEquals(5, y);
     assertEquals(3, z);
   }
+
+  proto[Symbol.unscopables] = {y: true};
+  object[Symbol.unscopables] = {x: true, y: undefined};
+  with (object) {
+    assertEquals(1, x);
+    assertEquals(5, y);
+    assertEquals(3, z);
+  }
 }
 runTest(TestOnProto);
 
 
 function TestSetBlockedOnProto(object, proto) {
   var x = 1;
   object.x = 2;
 
   with (object) {
     assertEquals(2, x);
@@ skipping 99 matching lines @@
   with (object) {
     for (var i = 0; i < 1000; i++) {
       if (i === 500) delete object[Symbol.unscopables].x;
       assertEquals(i < 500 ? 1 : 2, x);
     }
   }
 }
 TestChangeDuringWithWithPossibleOptimization4({});
 
 
+function TestChangeDuringWithWithPossibleOptimization4(object) {
+  var x = 1;
+  object.x = 2;
+  object[Symbol.unscopables] = {x: true};
+  with (object) {
+    for (var i = 0; i < 1000; i++) {
+      if (i === 500) object[Symbol.unscopables].x = undefined;
+      assertEquals(i < 500 ? 1 : 2, x);
+    }
+  }
+}
+TestChangeDuringWithWithPossibleOptimization4({});
+
+
 function TestAccessorReceiver(object, proto) {
   var x = 'local';
 
   Object.defineProperty(proto, 'x', {
     get: function() {
       assertEquals(object, this);
       return this.x_;
     },
     configurable: true
   });
@@ skipping 171 matching lines @@
     assertEquals(2, x);
   }
 }
 runTest(TestObjectsAsUnscopables);
 
 
 function TestAccessorOnUnscopables(object) {
   var x = 1;
   object.x = 2;
 
+  var calls = 0;
   var unscopables = {
     get x() {
-      assertUnreachable();
+      calls++;
+      return calls === 1 ? true : undefined;
     }
   };
 
   with (object) {
     assertEquals(2, x);
     object[Symbol.unscopables] = unscopables;
     assertEquals(1, x);
+    assertEquals(2, x);
   }
+  assertEquals(2, calls);
 }
 runTest(TestAccessorOnUnscopables);
 
 
 function TestLengthUnscopables(object, proto) {
   var length = 2;
   with (object) {
     assertEquals(1, length);
     object[Symbol.unscopables] = {length: true};
     assertEquals(2, length);
@@ skipping 96 matching lines @@
       throw new CustomError();
     }
   });
   assertThrows(function() {
     with (object) {
       x;
     }
   }, CustomError);
 }
 TestGetUnscopablesGetterThrows();
+
+
+function TestGetUnscopablesGetterThrows2() {
+  var object = {
+    get x() {
+      assertUnreachable();
+    }
+  };
+  function CustomError() {}
+
+  object[Symbol.unscopables] = {
+    get x() {
+      throw new CustomError();
+    }
+  };
+  assertThrows(function() {
+    with (object) {
+      x;
+    }
+  }, CustomError);
+}
+TestGetUnscopablesGetterThrows();