Recommit changing List.skip/take/revert returns Iterable and remove mappedBy.

Recommit changing List.skip/take/revert returns Iterable and remove mappedBy.

This reverts r18591.

Committed: https://code.google.com/p/dart/source/detail?r=18615

[Lasse Reichstein Nielsen, 2013-02-18 09:59:29]

https://codereview.chromium.org/12295009/diff/5004/sdk/lib/async/future_impl....
File sdk/lib/async/future_impl.dart (right):

https://codereview.chromium.org/12295009/diff/5004/sdk/lib/async/future_impl....
sdk/lib/async/future_impl.dart:114: factory _FutureImpl.wait(Iterable<Future>
futures) {
This implementation of wait is slightly safer than the previous one: It only
runs through the iterable once.
If using a non-list-based iterable, the previous version would run through it
twice (twice(!) to get the length, once to get values), and if the iterator had
side effects (A list.map(f) with f having side effects) that would not work as
expected.

[floitsch, 2013-02-18 10:34:09]

LGTM.