Fix missing static cast on Windows.

Review URL: https://chromiumcodereview.appspot.com/9963006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11190 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/regexp-macro-assembler-tracer.cc

@@ -205,7 +205,7 @@ class PrintablePrinter {
   const char* operator*() {
     if (character_ >= ' ' && character_ <= '~') {
       buffer_[0] = '(';
-      buffer_[1] = character_;
+      buffer_[1] = static_cast<char>(character_);
       buffer_[2] = ')';
       buffer_[3] = '\0';
     } else {