Make HTTP server close sockets when closed in idle state

Make HTTP server close sockets when closed in idle state

If a connection was in the idle state and the socket was closed by the
client the server did close the connection. This caused the server to
quickly run out of resources. There was a state check missing after a
state change.

Added a COSING state as well and a way to get the number of
connections if various states.

R=ager@google.com, ajohnsen@google.com

BUG=

Committed: https://code.google.com/p/dart/source/detail?r=15069

[Mads Ager (google), 2012-11-19 10:56:57]

LGTM

This seems related to: dartbug.com/4652?

https://codereview.chromium.org/11348127/diff/1/tests/standalone/io/http_shut...
File tests/standalone/io/http_shutdown_test.dart (right):

https://codereview.chromium.org/11348127/diff/1/tests/standalone/io/http_shut...
tests/standalone/io/http_shutdown_test.dart:134: // close the client and wait
for the server to loose all active
loose -> lose