Use FutureOr more and make Future.sync return the resulting Future directly.

Use FutureOr more and make Future.sync return the resulting Future directly.

When the computation passed to Future.sync returns a Future of the correct type,
then it's returned directly instead of wrapping it again.
(Until strong mode, we have an extra case for when it returns a Future of an
incorrect type, but that will eventually be removed).

This should improve the performance of Future.sync a bit.

Also adds missing Zone intercept for when the Future.sync computation throws.

Updates documentation for Future.doWhile.

Fixes #29202
BUG= http://dartbug.com/29202
R=floitsch@google.com

Committed: https://github.com/dart-lang/sdk/commit/d509ddb3fa9d2fb62dd2ef94010cd5dadbbd966b

[Lasse Reichstein Nielsen, 2017-03-31 08:53:04]

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

[floitsch, 2017-03-31 10:40:49]

LGTM.

[Lasse Reichstein Nielsen, 2017-03-31 10:41:12]

Description was changed from

==========
Use FutureOr more and make Future.sync return the resulting Future directly.

When the computation passed to Future.sync returns a Future of the correct type,
then it's returned directly instead of wrapping it again.
(Until strong mode, we have an extra case for when it returns a Future of an
incorrect type, but that will eventually be removed).

This should improve the performance of Future.sync a bit.

Also adds missing Zone intercept for when the Future.sync computation throws.

Updates documentation for Future.doWhile.

Fixes #29202
BUG= http://dartbug.com/29202
==========

to

==========
Use FutureOr more and make Future.sync return the resulting Future directly.

When the computation passed to Future.sync returns a Future of the correct type,
then it's returned directly instead of wrapping it again.
(Until strong mode, we have an extra case for when it returns a Future of an
incorrect type, but that will eventually be removed).

This should improve the performance of Future.sync a bit.

Also adds missing Zone intercept for when the Future.sync computation throws.

Updates documentation for Future.doWhile.

Fixes #29202
BUG= http://dartbug.com/29202
R=floitsch@google.com

Committed:
https://github.com/dart-lang/sdk/commit/d509ddb3fa9d2fb62dd2ef94010cd5dadbbd966b
==========

[Lasse Reichstein Nielsen, 2017-03-31 10:41:13]

Committed patchset #2 (id:20001) manually as
d509ddb3fa9d2fb62dd2ef94010cd5dadbbd966b (presubmit successful).