The debugger wire handler is implemented similarly to the io event handler.
A dedicated thread monitors the debugger port for incoming connection
requests. When a debugger is connected, the VM sends events messages
over the wire and handles debugger requests.
To start the VM with a debugger connection, use the option
--debug:<portnumber>. The VM pauses at the beginning of main()
and waits for a debugger to connect.
Subsequent changes will implement debugger commands one by one.
With this change, the VM only understands "resume" commands.
Review URL: https://chromiumcodereview.appspot.com//10357003
git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@7330 260f80e4-7a28-3924-810f-c04153c831b5
hausner@google.com