Add "has fast elements" bit to maps and use it in inlined keyed loads.

src/ic.cc

 // Copyright 2006-2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 974 matching lines @@
       stub = string_stub();
     } else if (object->IsJSObject()) {
       Handle<JSObject> receiver = Handle<JSObject>::cast(object);
       if (receiver->HasExternalArrayElements()) {
         stub = external_array_stub(receiver->GetElementsKind());
       } else if (receiver->HasIndexedInterceptor()) {
         stub = indexed_interceptor_stub();
       }
     }
     set_target(stub);
-    // For JSObjects that are not value wrappers and that do not have
-    // indexed interceptors, we initialize the inlined fast case (if
-    // present) by patching the inlined map check.
+    // For JSObjects with fast elements that are not value wrappers
+    // and that do not have indexed interceptors, we initialize the
+    // inlined fast case (if present) by patching the inlined map
+    // check.
     if (object->IsJSObject() &&
         !object->IsJSValue() &&
-        !JSObject::cast(*object)->HasIndexedInterceptor()) {
+        !JSObject::cast(*object)->HasIndexedInterceptor() &&
+        JSObject::cast(*object)->HasFastElements()) {
       Map* map = JSObject::cast(*object)->map();
       PatchInlinedLoad(address(), map);
     }
   }
 
   // Get the property.
   return Runtime::GetObjectProperty(object, key);
 }
 
 
@@ skipping 606 matching lines @@
 #undef ADDR
 };
 
 
 Address IC::AddressFromUtilityId(IC::UtilityId id) {
   return IC_utilities[id];
 }
 
 
 } }  // namespace v8::internal