Make sure we don't leak map transitions from AccessorPairs to the Javascript world.

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 5b44374591cefb4a10a25e89b7c1e90d365d6817..adbb2e139e83bd89f35406e5ce9e57a14b9153c6 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -1123,11 +1123,13 @@ static MaybeObject* GetOwnProperty(Isolate* isolate,
     elms->set(IS_ACCESSOR_INDEX, heap->true_value());
 
     AccessorPair* accessors = AccessorPair::cast(result.GetCallbackObject());
-    if (CheckAccess(*obj, *name, &result, v8::ACCESS_GET)) {
-      elms->set(GETTER_INDEX, accessors->GetComponent(ACCESSOR_GETTER));
+    Object* getter = accessors->GetComponent(ACCESSOR_GETTER);
+    if (!getter->IsMap() && CheckAccess(*obj, *name, &result, v8::ACCESS_GET)) {
+      elms->set(GETTER_INDEX, getter);
     }
-    if (CheckAccess(*obj, *name, &result, v8::ACCESS_SET)) {
-      elms->set(SETTER_INDEX, accessors->GetComponent(ACCESSOR_SETTER));
+    Object* setter = accessors->GetComponent(ACCESSOR_SETTER);
+    if (!setter->IsMap() && CheckAccess(*obj, *name, &result, v8::ACCESS_SET)) {
+      elms->set(SETTER_INDEX, setter);
     }
   } else {
     elms->set(IS_ACCESSOR_INDEX, heap->false_value());