Invoke dart2js lazily when using pub serve.

Invoke dart2js lazily when using pub serve.

R=rnystrom@google.com
BUG=16076
Committed: https://code.google.com/p/dart/source/detail?r=32579

[Bob Nystrom, 2014-02-11 19:08:47]

LGTM, but we should talk about what laziness means for error reporting.

https://codereview.chromium.org/139493010/diff/1/sdk/lib/_internal/pub/test/t...
File
sdk/lib/_internal/pub/test/transformer/dart2js/does_not_compile_until_its_output_is_requested_test.dart
(right):

https://codereview.chromium.org/139493010/diff/1/sdk/lib/_internal/pub/test/t...
sdk/lib/_internal/pub/test/transformer/dart2js/does_not_compile_until_its_output_is_requested_test.dart:30:
completion(equals("Build completed successfully")));
This highlights an interesting corner of the user experience. We may want to
change the wording of this message now since the user could infer it to mean
none of their assets have errors, which isn't the case.

Maybe it should be "Build finished" or something?

[nweiz, 2014-02-11 21:39:27]

On 2014/02/11 19:08:47, Bob Nystrom wrote:
> LGTM, but we should talk about what laziness means for error reporting.
> 
>
https://codereview.chromium.org/139493010/diff/1/sdk/lib/_internal/pub/test/t...
> File
>
sdk/lib/_internal/pub/test/transformer/dart2js/does_not_compile_until_its_output_is_requested_test.dart
> (right):
> 
>
https://codereview.chromium.org/139493010/diff/1/sdk/lib/_internal/pub/test/t...
>
sdk/lib/_internal/pub/test/transformer/dart2js/does_not_compile_until_its_output_is_requested_test.dart:30:
> completion(equals("Build completed successfully")));
> This highlights an interesting corner of the user experience. We may want to
> change the wording of this message now since the user could infer it to mean
> none of their assets have errors, which isn't the case.
> 
> Maybe it should be "Build finished" or something?

https://code.google.com/p/dart/issues/detail?id=16743

[nweiz, 2014-02-11 21:40:21]

Committed patchset #1 manually as r32579 (presubmit successful).