Revert "Return futures on Stream.cancel when possible."

Revert "Return futures on Stream.cancel when possible."

This reverts commit 1905ddafaa242883891e2fb2d706e2dfa059a71b.

Committed: https://github.com/dart-lang/sdk/commit/46a8579c1eb58f6a36a7d094d9b7824c92873de4

[floitsch, 2016-08-08 17:30:39]

floitsch@google.com changed reviewers:
+ lrn@google.com

[floitsch, 2016-08-08 17:30:39]

TBR.

Pub and dart_style fail.

pub: pub run test test/serve/web_socket/unserve_directory_test.dart

dartfmt:
python tools/test.py -mrelease  --use-sdk --write-test-outcome-log -t120
--copy-coredumps --use-public-packages
pkgbuild/third_party/pkg_tested/dart_style

[floitsch, 2016-08-08 17:31:10]

Description was changed from

==========
Revert "Return futures on Stream.cancel when possible."

This reverts commit 1905ddafaa242883891e2fb2d706e2dfa059a71b.
==========

to

==========
Revert "Return futures on Stream.cancel when possible."

This reverts commit 1905ddafaa242883891e2fb2d706e2dfa059a71b.

Committed:
https://github.com/dart-lang/sdk/commit/46a8579c1eb58f6a36a7d094d9b7824c92873de4
==========

[floitsch, 2016-08-08 17:31:12]

Committed patchset #1 (id:1) manually as
46a8579c1eb58f6a36a7d094d9b7824c92873de4 (presubmit successful).