Prevent modification of cached normalized maps....

src/objects-debug.cc

Index: src/objects-debug.cc
===================================================================
--- src/objects-debug.cc	(revision 5515)
+++ src/objects-debug.cc	(working copy)
@@ -649,8 +649,9 @@
 }
 
 
-void Map::NormalizedMapVerify() {
+void Map::SharedMapVerify() {
   MapVerify();
+  ASSERT(is_shared());
   ASSERT_EQ(Heap::empty_descriptor_array(), instance_descriptors());
   ASSERT_EQ(Heap::empty_fixed_array(), code_cache());
   ASSERT_EQ(0, pre_allocated_property_fields());
@@ -1381,7 +1382,7 @@
     for (int i = 0; i < length(); i++) {
       Object* e = get(i);
       if (e->IsMap()) {
-        Map::cast(e)->NormalizedMapVerify();
+        Map::cast(e)->SharedMapVerify();
       } else {
         ASSERT(e->IsUndefined());
       }