Add support for a "fine" barback log level.

Add support for a "fine" barback log level.

This level is not printed by default, but will be printed by pub if
--verbose is set.

Also update the observe/polymer version constraints. This change is
backwards-compatible from a transformer implementer's perspective, so the lower
bound doesn't need to be incremented.

BUG=16945
R=rnystrom@google.com

Committed: https://code.google.com/p/dart/source/detail?r=33000

[Bob Nystrom, 2014-02-24 22:19:55]

LGTM, though I hope revving barback doesn't cause too much friction in the
ecosystem.

https://codereview.chromium.org/166333003/diff/1/sdk/lib/_internal/pub/lib/sr...
File sdk/lib/_internal/pub/lib/src/barback/load_transformers.dart (left):

https://codereview.chromium.org/166333003/diff/1/sdk/lib/_internal/pub/lib/sr...
sdk/lib/_internal/pub/lib/src/barback/load_transformers.dart:488:
assert(message['level'] == 'Error');
Lame, I guess this means adding fine is a breaking change. :(

[nweiz, 2014-02-25 00:57:58]

Old pubs won't work with new barbacks, but the new pub will work with old
barbacks. I have another patch in the wings that will update pub's constraint on
barback to reflect that, which should limit the pain of revving.

[nweiz, 2014-02-25 01:24:33]

Committed patchset #1 manually as r33000 (presubmit successful).

[Siggi Cherem (dart-lang), 2014-02-25 17:56:07]

https://codereview.chromium.org/166333003/diff/1/pkg/barback/pubspec.yaml
File pkg/barback/pubspec.yaml (right):

https://codereview.chromium.org/166333003/diff/1/pkg/barback/pubspec.yaml#new...
pkg/barback/pubspec.yaml:11: version: 0.12.0-dev
mmm, not sure I follow why this is a breaking change. Could you use 0.11.2-dev
for this change?

https://codereview.chromium.org/166333003/diff/1/sdk/lib/_internal/pub/lib/sr...
File sdk/lib/_internal/pub/lib/src/barback.dart (right):

https://codereview.chromium.org/166333003/diff/1/sdk/lib/_internal/pub/lib/sr...
sdk/lib/_internal/pub/lib/src/barback.dart:34: final supportedVersion = new
Version(0, 12, 0);
If it can't be 0.11.2, could we support a wider version range here? (for example
">=0.11.0 <0.13.0 in this case?)

The reason I ask is because we'd like to not release polymer/observe at this
time. We are trying to bundle together a bunch of breaking changes together to
minimize user's disruption.

With the change as it is, we'll have to download the latest version of our
packages, modify them on the side to fix the constraint, and republish them. But
then there would be nothing in the repo history about this hot-fix. I prefer to
avoid it is possible (maybe I'd be less concerned doing that if we could have
our own branches in a separate repo where we could keep track of each version).

[Siggi Cherem (dart-lang), 2014-02-25 17:59:06]

https://codereview.chromium.org/166333003/diff/1/sdk/lib/_internal/pub/lib/sr...
File sdk/lib/_internal/pub/lib/src/barback.dart (right):

https://codereview.chromium.org/166333003/diff/1/sdk/lib/_internal/pub/lib/sr...
sdk/lib/_internal/pub/lib/src/barback.dart:34: final supportedVersion = new
Version(0, 12, 0);
On 2014/02/25 17:56:07, Siggi Cherem (dart-lang) wrote:
> If it can't be 0.11.2, could we support a wider version range here? (for
example
> ">=0.11.0 <0.13.0 in this case?)
> 
> The reason I ask is because we'd like to not release polymer/observe at this
> time. We are trying to bundle together a bunch of breaking changes together to
> minimize user's disruption.
> 
> With the change as it is, we'll have to download the latest version of our
> packages, modify them on the side to fix the constraint, and republish them.
But
> then there would be nothing in the repo history about this hot-fix. I prefer
to
> avoid it is possible (maybe I'd be less concerned doing that if we could have
> our own branches in a separate repo where we could keep track of each
version). 

Looking more closely I realize that that you depend on LogLevel.FINE in the code
so you wont be able to request 0.11.

Another idea - if it's possible to make barback's version 0.11.2, could this
'supportedVersion' start at 0.11.2 instead of 0.11.0?