does not use stack-allocated character as a one-element character
array.

The use at this site was actually safe (Ecma262Canonicalize will only
write to the first character of the array), but not obviously so.

BUG=17103

Review URL: http://codereview.chromium.org/159071

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2510 ce2b1a6d-e550-0410-aec6-3dcde31c8c00