ES6: Update unscopables to match spec

The spec ended up using Get(unscopables, propertyName) and
comparing the result to undefined instead of using Has.

BUG=v8:3632
LOG=Y
R=adamk, dslomov@chromium.org

Review URL: https://codereview.chromium.org/807893002

Cr-Commit-Position: refs/heads/master@{#25854}

src/contexts.cc

@@ -134,13 +134,14 @@ static Maybe<PropertyAttributes> UnscopableLookup(LookupIterator* it) {
     return Maybe<PropertyAttributes>();
   }
   if (!unscopables->IsSpecObject()) return attrs;
-  Maybe<bool> blacklist = JSReceiver::HasProperty(
-      Handle<JSReceiver>::cast(unscopables), it->name());
-  if (!blacklist.has_value) {
+  Handle<Object> blacklist;
+  MaybeHandle<Object> maybe_blacklist =
+      Object::GetProperty(unscopables, it->name());
+  if (!maybe_blacklist.ToHandle(&blacklist)) {
     DCHECK(isolate->has_pending_exception());
     return Maybe<PropertyAttributes>();
   }
-  if (blacklist.value) return maybe(ABSENT);
+  if (!blacklist->IsUndefined()) return maybe(ABSENT);
   return attrs;
 }
 

test/mjsunit/es6/unscopables.js

@@ -143,6 +143,13 @@ function TestBasics(object) {
     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);
 
@@ -161,6 +168,13 @@ function TestUnscopableChain(object) {
   with (object) {
     assertEquals(1, x);
   }
+
+  object[Symbol.unscopables] = {
+    __proto__: {x: undefined}
+  };
+  with (object) {
+    assertEquals(2, x);
+  }
 }
 runTest(TestUnscopableChain);
 
@@ -222,6 +236,14 @@ function TestOnProto(object, proto) {
     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);
 
@@ -341,6 +363,20 @@ function TestChangeDuringWithWithPossibleOptimization4(object) {
 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';
 
@@ -532,9 +568,11 @@ function TestAccessorOnUnscopables(object) {
   var x = 1;
   object.x = 2;
 
+  var calls = 0;
   var unscopables = {
     get x() {
-      assertUnreachable();
+      calls++;
+      return calls === 1 ? true : undefined;
     }
   };
 
@@ -542,7 +580,9 @@ function TestAccessorOnUnscopables(object) {
     assertEquals(2, x);
     object[Symbol.unscopables] = unscopables;
     assertEquals(1, x);
+    assertEquals(2, x);
   }
+  assertEquals(2, calls);
 }
 runTest(TestAccessorOnUnscopables);
 
@@ -659,3 +699,25 @@ function TestGetUnscopablesGetterThrows() {
   }, 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();

test/mjsunit/harmony/proxies-with-unscopables.js

@@ -74,12 +74,17 @@ function TestUseProxyAsUnscopables() {
   var calls = 0;
   var proxy = Proxy.create({
     has: function(key) {
-      calls++;
-      assertEquals('x', key);
-      return calls === 2;
+      assertUnreachable();
     },
     getPropertyDescriptor: function(key) {
-      assertUnreachable();
+      calls++;
+      assertEquals('x', key);
+      return {
+        value: calls === 2 ? true : undefined,
+        configurable: true,
+        enumerable: true,
+        writable: true,
+      };
     }
   });
 
@@ -107,12 +112,12 @@ function TestThrowInHasUnscopables() {
   var calls = 0;
   var proxy = Proxy.create({
     has: function(key) {
-      if (calls++ === 0) {
-        throw new CustomError();
-      }
       assertUnreachable();
     },
     getPropertyDescriptor: function(key) {
+      if (calls++ === 0) {
+        throw new CustomError();
+      }
       assertUnreachable();
     }
   });