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

src/factory.cc

 // Copyright 2006-2008 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 256 matching lines @@
   }
   // Adjust the map with the extra inobject properties.
   int inobject_properties =
       copy->inobject_properties() + extra_inobject_properties;
   copy->set_inobject_properties(inobject_properties);
   copy->set_unused_property_fields(inobject_properties);
   copy->set_instance_size(copy->instance_size() + instance_size_delta);
   return copy;
 }
 
+
 Handle<Map> Factory::CopyMapDropTransitions(Handle<Map> src) {
   CALL_HEAP_FUNCTION(src->CopyDropTransitions(), Map);
 }
 
 
+Handle<Map> Factory::GetFastElementsMap(Handle<Map> src) {
+  CALL_HEAP_FUNCTION(src->GetFastElementsMap(), Map);
+}
+
+
+Handle<Map> Factory::GetSlowElementsMap(Handle<Map> src) {
+  CALL_HEAP_FUNCTION(src->GetSlowElementsMap(), Map);
+}
+
+
 Handle<FixedArray> Factory::CopyFixedArray(Handle<FixedArray> array) {
   CALL_HEAP_FUNCTION(array->Copy(), FixedArray);
 }
 
 
 Handle<JSFunction> Factory::BaseNewFunctionFromSharedFunctionInfo(
     Handle<SharedFunctionInfo> function_info,
     Handle<Map> function_map,
     PretenureFlag pretenure) {
   CALL_HEAP_FUNCTION(Heap::AllocateFunction(*function_map,
@@ skipping 680 matching lines @@
     Execution::ConfigureInstance(instance,
                                  instance_template,
                                  pending_exception);
   } else {
     *pending_exception = false;
   }
 }
 
 
 } }  // namespace v8::internal