Convert a bunch of version solver code to use async/await.

Convert a bunch of version solver code to use async/await.

R=rnystrom@google.com

Committed: https://code.google.com/p/dart/source/detail?r=45612

[Bob Nystrom, 2015-05-07 16:23:34]

Two suggestions, but LGTM. Hot!

https://codereview.chromium.org/1125373002/diff/1/sdk/lib/_internal/pub/lib/s...
File sdk/lib/_internal/pub/lib/src/solver/backtracking_solver.dart (right):

https://codereview.chromium.org/1125373002/diff/1/sdk/lib/_internal/pub/lib/s...
sdk/lib/_internal/pub/lib/src/solver/backtracking_solver.dart:483: await
Future.doWhile(() async {
Can you use a normal while() loop here?

https://codereview.chromium.org/1125373002/diff/1/sdk/lib/_internal/pub/lib/s...
sdk/lib/_internal/pub/lib/src/solver/backtracking_solver.dart:550: return
Future.doWhile(() async {
And here?

[nweiz, 2015-05-07 19:50:09]

https://codereview.chromium.org/1125373002/diff/1/sdk/lib/_internal/pub/lib/s...
File sdk/lib/_internal/pub/lib/src/solver/backtracking_solver.dart (right):

https://codereview.chromium.org/1125373002/diff/1/sdk/lib/_internal/pub/lib/s...
sdk/lib/_internal/pub/lib/src/solver/backtracking_solver.dart:483: await
Future.doWhile(() async {
On 2015/05/07 16:23:34, Bob Nystrom wrote:
> Can you use a normal while() loop here?

No, but I should have included a TODO explaining why.

https://codereview.chromium.org/1125373002/diff/1/sdk/lib/_internal/pub/lib/s...
sdk/lib/_internal/pub/lib/src/solver/backtracking_solver.dart:550: return
Future.doWhile(() async {
On 2015/05/07 16:23:34, Bob Nystrom wrote:
> And here?

This one does have a comment.

[nweiz, 2015-05-07 19:50:30]

Code review changes

[nweiz, 2015-05-07 19:51:03]

Committed patchset #2 (id:20001) manually as 45612 (presubmit successful).

[nweiz, 2015-05-07 21:51:45]

TBR