Fixes leak in Process.runSync().

Fixes leak in Process.runSync().

This removes the call to _stdin._sink.destroy()
from my previous CL, which broke a test.
stdin is closed by the native implementation.
Closing again shouldn't cause a problem, but
it looks like destroy() attempts to do a lot
more than that.

OTOH adding the remove call is sufficient to
fix the leak, so let's just stick with that.

R=iposva@google.com

Committed: https://code.google.com/p/dart/source/detail?r=41395

[zra, 2014-10-29 14:07:16]

zra@google.com changed reviewers:
+ iposva@google.com, sgjesse@google.com

[Ivan Posva, 2014-10-29 14:31:19]

On 2014/10/29 14:07:16, zra wrote:

LGTM - ip

[zra, 2014-10-29 14:32:33]

Committed patchset #1 (id:1) manually as r41395 (presubmit successful).