Add remote debugging front end to developer shell.

Add remote debugging front end to developer shell.

D8 now supports demote debuggign of a V8 instance with the debugger agent enabled. Running D8 with the option --remote-debugger will try to connect to a V8 debugger agent and process the debugging protocol. The command line UI is the same as for the D8 in-process debugger as the same code is used for processing the debugger JSON.
Review URL: http://codereview.chromium.org/40011

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1411 ce2b1a6d-e550-0410-aec6-3dcde31c8c00