Version 3.23.13

Increase precision for base conversion for large integers (issue 3025).

Flatten cons string for single character substrings (Chromium issue 323041).

Performance and stability improvements on all platforms.

git-svn-id: https://v8.googlecode.com/svn/trunk@18108 ce2b1a6d-e550-0410-aec6-3dcde31c8c00