("narrowing conversion ... inside { } is ill-formed in C++11").

* src/mksnapshot.cc: Cast "char" to "unsigned char" when outputting snapshot.
* test/cctest/test-regexp.cc: Use static_cast to uc16 as the char
literal is signed.

Review URL: http://codereview.chromium.org/8825003
Patch from Tobias Burnus <burnus@net-b.de>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10241 ce2b1a6d-e550-0410-aec6-3dcde31c8c00