Use GetProperty for getting elements.

src/utils.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_UTILS_H_
 #define V8_UTILS_H_
 
 #include <limits.h>
 #include <stdlib.h>
 #include <string.h>
@@ skipping 1672 matching lines @@
   }
 
   // Convert string to uint32 array index; character by character.
   int d = ch - '0';
   if (d < 0 || d > 9) return false;
   uint32_t result = d;
   while (stream->HasMore()) {
     d = stream->GetNext() - '0';
     if (d < 0 || d > 9) return false;
     // Check that the new result is below the 32 bit limit.
-    if (result > 429496729U - ((d > 5) ? 1 : 0)) return false;
+    if (result > 429496729U - ((d + 3) >> 3)) return false;
     result = (result * 10) + d;
   }
 
   *index = result;
   return true;
 }
 
 
 // Returns current value of top of the stack. Works correctly with ASAN.
 DISABLE_ASAN
 inline uintptr_t GetCurrentStackPosition() {
   // Takes the address of the limit variable in order to find out where
   // the top of stack is right now.
   uintptr_t limit = reinterpret_cast<uintptr_t>(&limit);
   return limit;
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_UTILS_H_