Devirtualize Parser

* src/parser.h: No one inherits from Parser, so the destructor can be
  non-virtual, removing the need for Parser to have a vtable. Also add
  BASE_EMBEDDED to it and to RegExpParser.

BUG=

Review URL: https://codereview.chromium.org/13640007
Patch from Andy Wingo <wingo@igalia.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14162 ce2b1a6d-e550-0410-aec6-3dcde31c8c00