Fix assert on Mozilla test after String split optimization.

src/heap.cc

 // Copyright 2011 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 2264 matching lines @@
 }
 
 
 void StringSplitCache::Enter(Heap* heap,
                              FixedArray* cache,
                              String* string,
                              String* pattern,
                              FixedArray* array) {
   if (!string->IsSymbol() || !pattern->IsSymbol()) return;
   uintptr_t hash = string->Hash();
-  array->set_map(heap->fixed_cow_array_map());
   uintptr_t index = ((hash & (kStringSplitCacheSize - 1)) &
       ~(kArrayEntriesPerCacheEntry - 1));
   if (cache->get(index + kStringOffset) == Smi::FromInt(0)) {
     cache->set(index + kStringOffset, string);
     cache->set(index + kPatternOffset, pattern);
     cache->set(index + kArrayOffset, array);
     return;
   }
   uintptr_t index2 =
       ((index + kArrayEntriesPerCacheEntry) & (kStringSplitCacheSize - 1));
@@ skipping 12 matching lines @@
   if (array->length() < 100) {  // Limit how many new symbols we want to make.
     for (int i = 0; i < array->length(); i++) {
       String* str = String::cast(array->get(i));
       Object* symbol;
       MaybeObject* maybe_symbol = heap->LookupSymbol(str);
       if (maybe_symbol->ToObject(&symbol)) {
         array->set(i, symbol);
       }
     }
   }
+  array->set_map(heap->fixed_cow_array_map());
 }
 
 
 void StringSplitCache::Clear(FixedArray* cache) {
   for (int i = 0; i < kStringSplitCacheSize; i++) {
     cache->set(i, Smi::FromInt(0));
   }
 }
 
 
@@ skipping 3898 matching lines @@
 }
 
 
 void ExternalStringTable::TearDown() {
   new_space_strings_.Free();
   old_space_strings_.Free();
 }
 
 
 } }  // namespace v8::internal