Store transitioned JSArray maps in global context

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index 752b220e5b56742978049a70544877622bb15266..1de8b70214e8e6b0b504cc6cd9f3ca3cdd5d0bce 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -1,4 +1,4 @@
-// Copyright 2011 the V8 project authors. All rights reserved.
+// Copyright 2012 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:
@@ -894,15 +894,12 @@ void Genesis::InitializeGlobal(Handle<GlobalObject> inner_global,
             factory->NewForeign(&Accessors::ArrayLength),
             static_cast<PropertyAttributes>(DONT_ENUM | DONT_DELETE));
 
-    // Cache the fast JavaScript array map
-    global_context()->set_js_array_map(array_function->initial_map());
-    global_context()->js_array_map()->set_instance_descriptors(
-        *array_descriptors);
     // array_function is used internally. JS code creating array object should
     // search for the 'Array' property on the global object and use that one
     // as the constructor. 'Array' property on a global object can be
     // overwritten by JS code.
     global_context()->set_array_function(*array_function);
+    array_function->initial_map()->set_instance_descriptors(*array_descriptors);
   }
 
   {  // --- N u m b e r ---
@@ -1646,7 +1643,7 @@ bool Genesis::InstallNatives() {
     MaybeObject* maybe_map =
         array_function->initial_map()->CopyDropTransitions();
     Map* new_map;
-    if (!maybe_map->To<Map>(&new_map)) return maybe_map;
+    if (!maybe_map->To<Map>(&new_map)) return false;
     new_map->set_elements_kind(FAST_ELEMENTS);
     array_function->set_initial_map(new_map);
 
@@ -1745,17 +1742,15 @@ bool Genesis::InstallNatives() {
     initial_map->set_prototype(*array_prototype);
 
     // Update map with length accessor from Array and add "index" and "input".
-    Handle<Map> array_map(global_context()->js_array_map());
-    Handle<DescriptorArray> array_descriptors(
-        array_map->instance_descriptors());
-    ASSERT_EQ(1, array_descriptors->number_of_descriptors());
-
     Handle<DescriptorArray> reresult_descriptors =
         factory()->NewDescriptorArray(3);
-
     DescriptorArray::WhitenessWitness witness(*reresult_descriptors);
 
-    reresult_descriptors->CopyFrom(0, *array_descriptors, 0, witness);
+    JSFunction* array_function = global_context()->array_function();
+    Handle<DescriptorArray> array_descriptors(
+        array_function->initial_map()->instance_descriptors());
+    int index = array_descriptors->SearchWithCache(heap()->length_symbol());
+    reresult_descriptors->CopyFrom(0, *array_descriptors, index, witness);
 
     int enum_index = 0;
     {