implement configuration specific imports

[vsmenon]

From @jmesserly on June 22, 2016 23:36

See SDK bug: #24581

Guessing this should be pretty easy, mostly plumbing through the right configuration to Analyzer.

CC @alan-knight

Copied from original issue: dart-archive/dev_compiler#595

[vsmenon]

From @anders-sandholm on September 13, 2016 10:53

When do you expect to see this land?

Would be great to get this landed. Look's like this might be the last bit missing in enabling a re-write of package http to use config-specific imports instead of mirrors.

[vsmenon]

Not scheduled yet.

[mit-mit]

Any news here? We now have actual usage of this in the SDK; see package resource.

Updating to P1.

[vsmenon]

This should fixed by #27511 ( @bwilkerson - is there anything more?) - I'll up that to P1 as well.

[bwilkerson]

Not that I know of, except that there is now discussion of de-scoping configuration specific imports.

[vsmenon]

@munificent - not sure what the status of this is. It might just work. @jmesserly plumbed some support for defined variables recently. Do we need this for 1.5 or earlier?

[mit-mit]

We need this for 1.22; Flutter also needs it now.

[munificent]

@munificent - not sure what the status of this is.

Me either. I handed it off to @floitschG ages ago.

Do we need this for 1.5 or earlier?

No, it's not a 1.5 milestone language issue.

[mit-mit]

No, it's not a 1.5 milestone language issue.

Correct. This pre-dates 1.50, and should have been completed long ago. Can we please just get this done now?

CC @dgrove in case additional discussion is needed.