dart2js: Fix check for support of reflection.

dart2js: Fix check for support of reflection.

R=johnniwinther@google.com

Committed: https://github.com/dart-lang/sdk/commit/0d1ca80570f7d037281ad2223d6cf3580918b248

[floitsch, 2015-07-16 18:02:32]

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

[Johnni Winther, 2015-07-16 18:14:30]

lgtm

https://codereview.chromium.org/1244473002/diff/1/pkg/compiler/lib/src/warnin...
File pkg/compiler/lib/src/warnings.dart (right):

https://codereview.chromium.org/1244473002/diff/1/pkg/compiler/lib/src/warnin...
pkg/compiler/lib/src/warnings.dart:2529: "dart:mirrors library is not supported
when using this backend.");
Which backend? Can you provide more info and maybe howToFix to the user?

[floitsch, 2015-07-17 13:16:19]

https://codereview.chromium.org/1244473002/diff/1/pkg/compiler/lib/src/warnin...
File pkg/compiler/lib/src/warnings.dart (right):

https://codereview.chromium.org/1244473002/diff/1/pkg/compiler/lib/src/warnin...
pkg/compiler/lib/src/warnings.dart:2529: "dart:mirrors library is not supported
when using this backend.");
On 2015/07/16 18:14:29, Johnni Winther wrote:
> Which backend? Can you provide more info and maybe howToFix to the user?

I wondered. (After all I removed the old one).
I think the complexity is not worth the effort:
- the emitter knows if it supports reflection.
- the choice of how the emitter was selected is not completely clear. Currently
it's a compile-time constant. It should become a flag, and could also change
depending on different things (like using the startup-emitter for CSP
compilation if there is no reflection).

All in all, I expect this to be a rare problem.

[floitsch, 2015-07-17 13:16:45]

Committed patchset #1 (id:1) manually as
0d1ca80570f7d037281ad2223d6cf3580918b248 (presubmit successful).