Fixing Windows build.

src/conversions.cc

 // Copyright 2006-2008 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 298 matching lines @@
       digit = static_cast<char>(*current) - 'A' + 10;
     } else {
       if (allow_trailing_junk || !AdvanceToNonspace(&current, end)) {
         break;
       } else {
         return JUNK_STRING_VALUE;
       }
     }
 
     number = number * radix + digit;
-    int overflow = number >> 53;
+    int overflow = static_cast<int>(number >> 53);
     if (overflow != 0) {
       // Overflow occurred. Need to determine which direction to round the
       // result.
       int overflow_bits_count = 1;
       while (overflow > 1) {
         overflow_bits_count++;
         overflow >>= 1;
       }
 
       int dropped_bits_mask = ((1 << overflow_bits_count) - 1);
-      int dropped_bits = number & dropped_bits_mask;
+      int dropped_bits = static_cast<int>(number) & dropped_bits_mask;
       number >>= overflow_bits_count;
       exponent = overflow_bits_count;
 
       bool zero_tail = true;
       while (true) {
         ++current;
         if (current == end || !isDigit(*current, radix)) break;
         zero_tail = zero_tail && *current == '0';
         exponent += radix_log_2;
       }
@@ skipping 694 matching lines @@
   // Allocate result and fill in the parts.
   StringBuilder builder(result_size + 1);
   builder.AddSubstring(integer_buffer + integer_pos + 1, integer_part_size);
   if (decimal_pos > 0) builder.AddCharacter('.');
   builder.AddSubstring(decimal_buffer, decimal_pos);
   return builder.Finalize();
 }
 
 
 } }  // namespace v8::internal