Replaced multiple calls to AddNumber with a single AddString.
AddNumber may now print the value directly into the output buffer.

BUG=none
TEST=none

Review URL: https://chromiumcodereview.appspot.com/9395087
Patch from Alexei Filippov <alexeif@chromium.org>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10784 ce2b1a6d-e550-0410-aec6-3dcde31c8c00