pub: don't start the admin server if no --admin-port flag was given.

pub: don't start the admin server if no --admin-port flag was given.

`pub serve` used to bind its admin port to the port below the main port. For example `pub serve --port=8081` would automatically bind its admin port to 8080.
With this change the admin server is only started if an --admin-port flag was provided.

BUG= http://dartbug.com/20922
R=rnystrom@google.com

Committed: https://code.google.com/p/dart/source/detail?r=45614
Reverted: https://code.google.com/p/dart/source/detail?r=45633

Committed: https://code.google.com/p/dart/source/detail?r=45675

[floitsch, 2015-05-06 22:14:11]

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

[Bob Nystrom, 2015-05-06 22:20:28]

https://codereview.chromium.org/1126403002/diff/1/sdk/lib/_internal/pub/lib/s...
File sdk/lib/_internal/pub/lib/src/barback/asset_environment.dart (right):

https://codereview.chromium.org/1126403002/diff/1/sdk/lib/_internal/pub/lib/s...
sdk/lib/_internal/pub/lib/src/barback/asset_environment.dart:192: if (port ==
null) port = 0;
Instead of picking an ephemeral port, if the user didn't specifically ask for an
admin server, let's just not bind one at all.

However, you may not be able to do this. Pub may still use the admin server
internally for the isolates that transformers are loaded into.

In that case, you could either just not allow the WebSocket connection, or
(easier) just not do this change at all.

[floitsch, 2015-05-06 23:01:06]

https://codereview.chromium.org/1126403002/diff/1/sdk/lib/_internal/pub/lib/s...
File sdk/lib/_internal/pub/lib/src/barback/asset_environment.dart (right):

https://codereview.chromium.org/1126403002/diff/1/sdk/lib/_internal/pub/lib/s...
sdk/lib/_internal/pub/lib/src/barback/asset_environment.dart:192: if (port ==
null) port = 0;
On 2015/05/06 22:20:27, Bob Nystrom wrote:
> Instead of picking an ephemeral port, if the user didn't specifically ask for
an
> admin server, let's just not bind one at all.
> 
> However, you may not be able to do this. Pub may still use the admin server
> internally for the isolates that transformers are loaded into.
> 
> In that case, you could either just not allow the WebSocket connection, or
> (easier) just not do this change at all.

Done.

[Bob Nystrom, 2015-05-07 16:04:14]

LGTM!

[floitsch, 2015-05-07 20:02:16]

Committed patchset #2 (id:20001) manually as 45614 (presubmit successful).

[floitsch, 2015-05-09 02:08:20]

Had to revert, and fix the test-file.
Resubmitting.

[floitsch, 2015-05-09 02:08:42]

Committed patchset #3 (id:40001) manually as 45675 (presubmit successful).