Fix wrong detection of duplicate definition of function types (issue 187).

Fix wrong detection of duplicate definition of function types (issue 187).
Duplicate import of a function type alias must be detected, but duplicate
import of a compiler generated canonical function type is necessary for proper
class resolution and is permitted.
Add tests.
Committed: https://code.google.com/p/dart/source/detail?r=658

[siva, 2011-10-24 22:19:03]

LGTM.

I would add one more negative test to the mix to confirm
that we do the right lookup when adding function alias
type names.

e.g Library6NegativeTest.dart
#import("Library5a.dart");
typedef int Fun();  // Expect this to conflict during parse.
main() {
}

[regis, 2011-10-24 22:27:20]

On 2011/10/24 22:19:03, asiva wrote:
> LGTM.
> 
> I would add one more negative test to the mix to confirm
> that we do the right lookup when adding function alias
> type names.
> 
> e.g Library6NegativeTest.dart
> #import("Library5a.dart");
> typedef int Fun();  // Expect this to conflict during parse.
> main() {
> }

Done