Revert r4782. Fix issues 728, 732.

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 4832 matching lines @@
 
   *index = result;
   return true;
 }
 
 
 bool String::SlowAsArrayIndex(uint32_t* index) {
   if (length() <= kMaxCachedArrayIndexLength) {
     Hash();  // force computation of hash code
     uint32_t field = hash_field();
-    if ((field & kIsArrayIndexMask) == 0) return false;
+    if ((field & kIsNotArrayIndexMask) != 0) return false;
     // Isolate the array index form the full hash field.
     *index = (kArrayIndexHashMask & field) >> kHashShift;
     return true;
   } else {
     StringInputBuffer buffer(this);
     return ComputeArrayIndex(&buffer, index, length());
   }
 }
 
 
 static inline uint32_t HashField(uint32_t hash,
                                  bool is_array_index,
                                  int length = -1) {
   uint32_t result = (hash << String::kHashShift);
   if (is_array_index) {
     // 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));
-    result |= String::kIsArrayIndexMask;
+    ASSERT(String::kMaxArrayIndexSize < (1 << String::kArrayIndexValueBits));
+    result &= ~String::kIsNotArrayIndexMask;
     result |= length << String::kArrayIndexHashLengthShift;
+  } else {
+    result |= String::kIsNotArrayIndexMask;
   }
   return result;
 }
 
 
 uint32_t StringHasher::GetHashField() {
   ASSERT(is_valid());
   if (length_ <= String::kMaxHashCalcLength) {
     if (is_array_index()) {
       return v8::internal::HashField(array_index(), true, length_);
@@ skipping 3828 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