Reapply r5603 with additional fix: use OS::StrNCpy instead of posix strncpy.

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 336 matching lines @@
       if (current == end) break;
     }
 
     if (!allow_trailing_junk && AdvanceToNonspace(&current, end)) {
       return JUNK_STRING_VALUE;
     }
 
     ASSERT(buffer_pos < kBufferSize);
     buffer[buffer_pos] = '\0';
     Vector<char> buffer_vector(buffer, buffer_pos);
-    return sign ? -strtod(buffer_vector, NULL) : strtod(buffer_vector, NULL);
+    return sign ? -Strtod(buffer_vector, 0) : Strtod(buffer_vector, 0);
   }
 
   // The following code causes accumulating rounding error for numbers greater
   // than ~2^56. It's explicitly allowed in the spec: "if R is not 2, 4, 8, 10,
   // 16, or 32, then mathInt may be an implementation-dependent approximation to
   // the mathematical integer value" (15.1.2.2).
 
   int lim_0 = '0' + (radix < 10 ? radix : 10);
   int lim_a = 'a' + (radix - 10);
   int lim_A = 'A' + (radix - 10);
@@ skipping 278 matching lines @@
   }
 
   if (nonzero_digit_dropped) {
     buffer[buffer_pos++] = '1';
     exponent--;
   }
 
   ASSERT(buffer_pos < kBufferSize);
   buffer[buffer_pos] = '\0';
 
-  double converted = strtod(Vector<char>(buffer, buffer_pos), exponent);
+  double converted = Strtod(Vector<char>(buffer, buffer_pos), exponent);
   return sign? -converted: converted;
 }
 
 
 double StringToDouble(String* str, int flags, double empty_string_val) {
   StringShape shape(str);
   if (shape.IsSequentialAscii()) {
     const char* begin = SeqAsciiString::cast(str)->GetChars();
     const char* end = begin + str->length();
     return InternalStringToDouble(begin, end, flags, empty_string_val);
@@ skipping 464 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