Remove LookupTransitionOrDescriptor altogether.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index d76c1d7c130db1cef50791602def1fac02431b1e..50a5335a0ffa9ce5edaea9f4b8cf289bd5d8a689 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -1670,8 +1670,8 @@ void HLoadNamedField::PrintDataTo(StringStream* stream) {
 
 
 // Returns true if an instance of this map can never find a property with this
-// name in its prototype chain.  This means all prototypes up to the top are
-// fast and don't have the name in them.  It would be good if we could optimize
+// name in its prototype chain. This means all prototypes up to the top are fast
+// and don't have the name in them. It would be good if we could optimize
 // polymorphic loads where the property is sometimes found in the prototype
 // chain.
 static bool PrototypeChainCanNeverResolve(
@@ -1689,13 +1689,9 @@ static bool PrototypeChainCanNeverResolve(
 
     LookupResult lookup(isolate);
     Map* map = JSObject::cast(current)->map();
-    map->LookupTransitionOrDescriptor(NULL, *name, &lookup);
-    if (lookup.IsFound()) {
-      if (!lookup.IsTransition()) return false;
-    } else if (!lookup.IsCacheable()) {
-      return false;
-    }
-
+    map->LookupDescriptor(NULL, *name, &lookup);
+    if (lookup.IsFound()) return false;
+    if (!lookup.IsCacheable()) return false;
     current = JSObject::cast(current)->GetPrototype();
   }
   return true;
@@ -1720,7 +1716,7 @@ HLoadNamedFieldPolymorphic::HLoadNamedFieldPolymorphic(HValue* context,
        ++i) {
     Handle<Map> map = types->at(i);
     LookupResult lookup(map->GetIsolate());
-    map->LookupTransitionOrDescriptor(NULL, *name, &lookup);
+    map->LookupDescriptor(NULL, *name, &lookup);
     if (lookup.IsFound()) {
       switch (lookup.type()) {
         case FIELD: {
@@ -1739,10 +1735,6 @@ HLoadNamedFieldPolymorphic::HLoadNamedFieldPolymorphic(HValue* context,
         case CALLBACKS:
           break;
         case TRANSITION:
-          if (PrototypeChainCanNeverResolve(map, name)) {
-            negative_lookups.Add(types->at(i), zone);
-          }
-          break;
         case INTERCEPTOR:
         case NONEXISTENT:
         case NORMAL:
@@ -1750,10 +1742,9 @@ HLoadNamedFieldPolymorphic::HLoadNamedFieldPolymorphic(HValue* context,
           UNREACHABLE();
           break;
       }
-    } else if (lookup.IsCacheable()) {
-      if (PrototypeChainCanNeverResolve(map, name)) {
-        negative_lookups.Add(types->at(i), zone);
-      }
+    } else if (lookup.IsCacheable() &&
+               PrototypeChainCanNeverResolve(map, name)) {
+      negative_lookups.Add(types->at(i), zone);
     }
   }