Emit compile-time error on duplicate parameter names in typedefs.

Emit compile-time error on duplicate parameter names in typedefs.

BUG=dartbug.com/7202
R=ngeoffray@google.com

Committed: https://code.google.com/p/dart/source/detail?r=27640

[karlklose, 2013-09-16 14:28:20]

PTAL.

[ngeoffray, 2013-09-16 16:12:49]

LGTM

https://codereview.chromium.org/23463032/diff/3001/sdk/lib/_internal/compiler...
File sdk/lib/_internal/compiler/implementation/resolution/members.dart (right):

https://codereview.chromium.org/23463032/diff/3001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/resolution/members.dart:1740: void
reportDuplicateDefinition(name, Spannable definition,
Could you add (/* SourceString|Node */ name, ...) ?

https://codereview.chromium.org/23463032/diff/3001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/resolution/members.dart:2318: if
(seenNamedArguments.containsKey(source)) {
Do you still need this check? It seems that the defineElement should do it for
you.

[ngeoffray, 2013-09-16 16:25:27]

https://codereview.chromium.org/23463032/diff/3001/sdk/lib/_internal/compiler...
File sdk/lib/_internal/compiler/implementation/resolution/members.dart (right):

https://codereview.chromium.org/23463032/diff/3001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/resolution/members.dart:3338:
FunctionSignature signature = SignatureResolver.analyze(
I would have thought that SignatureResolver would detect the duplicates.

[karlklose, 2013-09-19 06:57:24]

Committed patchset #2 manually as r27640 (presubmit successful).