ES6 Unscopables

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index d980d327aa89640d2b44cbef8e08b58be0eb3257..e7bd3e8a0ba4658a5b03655aa8f51474777088e1 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -41,6 +41,7 @@
 #include "src/smart-pointers.h"
 #include "src/string-search.h"
 #include "src/stub-cache.h"
+#include "src/unscopables.h"
 #include "src/uri.h"
 #include "src/v8threads.h"
 #include "src/vm-state-inl.h"
@@ -9091,6 +9092,30 @@ static Object* ComputeReceiverForNonGlobal(Isolate* isolate,
 }
 
 
+static ObjectPair LoadWithContextSlot(Isolate* isolate, Handle<String> name,
+                                      Handle<JSReceiver> object,
+                                      Handle<Object> receiver_handle) {
+  UnscopableLookup lookup(isolate, name, object);
+  if (lookup.HasError()) {
+    return MakePair(isolate->heap()->exception(), NULL);
+  }
+  if (lookup.Found()) {
+    // The property might be a getter that is normally shadowed but due to the
+    // unscopables we found it further up the prototype chain. Therefore we need
+    // to ensure that we are using the right receiver and holder when we get the
+    // value.
+    Handle<Object> value;
+    LookupIterator it(object, name, lookup.GetHolder());
+    ASSIGN_RETURN_ON_EXCEPTION_VALUE(
+        isolate, value, Object::GetProperty(&it),
+        MakePair(isolate->heap()->exception(), NULL));
+    return MakePair(*value, *receiver_handle);
+  }
+  return MakePair(isolate->heap()->undefined_value(),
+                  isolate->heap()->undefined_value());
+}
+
+
 static ObjectPair LoadContextSlotHelper(Arguments args,
                                         Isolate* isolate,
                                         bool throw_error) {
@@ -9165,6 +9190,10 @@ static ObjectPair LoadContextSlotHelper(Arguments args,
                 : ComputeReceiverForNonGlobal(isolate, JSObject::cast(*object)),
         isolate);
 
+    if (FLAG_harmony_unscopables && context->IsWithContext()) {
+      return LoadWithContextSlot(isolate, name, object, receiver_handle);
+    }
+
     // No need to unhole the value here.  This is taken care of by the
     // GetProperty function.
     Handle<Object> value;