Make CompilationInfo::~CompilationInfo() virtual so that CompilationInfoWithZone destructs correctly.

BUG=
TEST=

Review URL: https://chromiumcodereview.appspot.com/10789039

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12114 ce2b1a6d-e550-0410-aec6-3dcde31c8c00