Removing a wrong check....

src/objects.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 4972 matching lines @@
     // Isolate the array index form the full hash field.
     *index = (kArrayIndexHashMask & field) >> kHashShift;
     return true;
   } else {
     StringInputBuffer buffer(this);
     return ComputeArrayIndex(&buffer, index, length());
   }
 }
 
 
-uint32_t StringHasher::MakeCachedArrayIndex(uint32_t value, int length) {
-  value <<= String::kHashShift;
+uint32_t StringHasher::MakeArrayIndexHash(uint32_t value, int length) {
   // For array indexes mix the length into the hash as an array index could
   // be zero.
   ASSERT(length > 0);
   ASSERT(length <= String::kMaxArrayIndexSize);
   ASSERT(TenToThe(String::kMaxCachedArrayIndexLength) <
          (1 << String::kArrayIndexValueBits));
-  ASSERT(String::kMaxArrayIndexSize < (1 << String::kArrayIndexValueBits));
-  value &= ~String::kIsNotArrayIndexMask;
+
+  value <<= String::kHashShift;
   value |= length << String::kArrayIndexHashLengthShift;
+
+  ASSERT((value & String::kIsNotArrayIndexMask) == 0);
+  ASSERT((length > String::kMaxCachedArrayIndexLength) ||
+         (value & String::kContainsCachedArrayIndexMask) == 0);
   return value;
 }
 
 
 uint32_t StringHasher::GetHashField() {
   ASSERT(is_valid());
   if (length_ <= String::kMaxHashCalcLength) {
     if (is_array_index()) {
-      return MakeCachedArrayIndex(array_index(), length_);
+      return MakeArrayIndexHash(array_index(), length_);
     }
     return (GetHash() << String::kHashShift) | String::kIsNotArrayIndexMask;
   } else {
     return (length_ << String::kHashShift) | String::kIsNotArrayIndexMask;
   }
 }
 
 
 uint32_t String::ComputeHashField(unibrow::CharacterStream* buffer,
                                   int length) {
@@ skipping 3865 matching lines @@
   if (break_point_objects()->IsUndefined()) return 0;
   // Single beak point.
   if (!break_point_objects()->IsFixedArray()) return 1;
   // Multiple break points.
   return FixedArray::cast(break_point_objects())->length();
 }
 #endif
 
 
 } }  // namespace v8::internal