Fix handling of accessors on trunk. This is a combination of

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
===================================================================
--- src/hydrogen-instructions.cc	(revision 12276)
+++ src/hydrogen-instructions.cc	(working copy)
@@ -1682,6 +1682,7 @@
     if (current->IsJSGlobalProxy() ||
         current->IsGlobalObject() ||
         !current->IsJSObject() ||
+        JSObject::cast(current)->map()->has_named_interceptor() ||
         JSObject::cast(current)->IsAccessCheckNeeded() ||
         !JSObject::cast(current)->HasFastProperties()) {
       return false;
@@ -1743,6 +1744,11 @@
           break;
       }
     } else if (lookup.IsCacheable() &&
+               // For dicts the lookup on the map will fail, but the object may
+               // contain the property so we cannot generate a negative lookup
+               // (which would just be a map check and return undefined).
+               !map->is_dictionary_map() &&
+               !map->has_named_interceptor() &&
                PrototypeChainCanNeverResolve(map, name)) {
       negative_lookups.Add(types->at(i), zone);
     }