Add --version option to dart2js and add version information (if available) to generated code.

Add --version option to dart2js and add version information (if available) to generated code.

Remove the 'Using snapshot ...' comment from sdk/bin/dart2js since we are
now relatively sure it works.

R=ahe@google.com, ngeoffray@google.com
BUG=http://dartbug.com/4439, http://dartbug.com/9848

Committed: https://code.google.com/p/dart/source/detail?r=23355

[ngeoffray, 2013-05-29 13:56:40]

LGTM

https://codereview.chromium.org/15957006/diff/1/sdk/lib/_internal/compiler/im...
File sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart (right):

https://codereview.chromium.org/15957006/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart:3192: : '
version: $BUILD_ID';
Add a '.' at the end?

[kasperl, 2013-05-29 14:01:31]

https://codereview.chromium.org/15957006/diff/1/sdk/lib/_internal/compiler/im...
File sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart (right):

https://codereview.chromium.org/15957006/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart:3192: : '
version: $BUILD_ID';
On 2013/05/29 13:56:40, ngeoffray wrote:
> Add a '.' at the end?

I think it would look a little bit weird because the version number may have
dots in it too. I'm not sure I'm overly fond of the format (version: ID), but
I've tried to make it look like what the VM prints.

[aam-me, 2013-05-29 15:04:09]

Hi Kasper,

-  # TODO(ahe): Remove the following line when we are relatively sure it works.
-  echo Using snapshot "$SNAPSHOT" 1>&2

  do you want to remove "Using snapshot" message from windows dart2js.bat as
well then?

Alexander Aprelev.

[ahe, 2013-05-29 15:18:10]

LGTM!

I'd add a period after the version number.

[kasperl, 2013-05-29 16:54:44]

On 2013/05/29 15:18:10, ahe wrote:
> LGTM!
> 
> I'd add a period after the version number.

It seems I'm outnumbered :-) I will add the dot.

[kasperl, 2013-05-29 17:01:17]

Committed patchset #2 manually as r23355 (presubmit successful).

[ahe, 2013-05-29 17:36:54]

https://codereview.chromium.org/15957006/diff/7001/sdk/lib/_internal/compiler...
File sdk/lib/_internal/compiler/implementation/js_backend/js_backend.dart
(right):

https://codereview.chromium.org/15957006/diff/7001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/js_backend/js_backend.dart:16: import
'../dart2js.dart' show BUILD_ID;
How did I overlook this :-)

Get the version from the compiler object: compiler.buildId.