If an Isolate touches the 'stdio' getter, a _NativeSocket with
attached finalizer is created for it. Previously, when such an
Isolate exited, the finalizer would close the underlying
file descriptor. This CL changes the finalizer for stdin such
that the native objects will be cleaned up, but the underlying
file descriptor will not be closed. The underlying file
descriptor will now only be closed if the stdin stream
subscription is explicitly canceled.
Accessing the stdin getter after the stream is explicitly
canceled will result in a FileSystemException.
See also: https://github.com/dart-lang/test/issues/583fixes#29229R=rmacnak@google.com
Review-Url: https://codereview.chromium.org/2791423002 .
Zachary Anderson
8c9c54d833