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

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

BUG=7202
R=johnniwinther@google.com

Committed: https://code.google.com/p/dart/source/detail?r=27798

[karlklose, 2013-09-23 07:59:20]

Patch set 1 is the already reviewed CL, patch set 2 fixes a checked mode issue
in dart2dart.

[Johnni Winther, 2013-09-23 08:06:18]

lgtm

https://codereview.chromium.org/24326003/diff/3001/sdk/lib/_internal/compiler...
File
sdk/lib/_internal/compiler/implementation/dart_backend/placeholder_collector.dart
(right):

https://codereview.chromium.org/24326003/diff/3001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/dart_backend/placeholder_collector.dart:271:
} else if (Elements.isLocal(element) && !isTypedefParameter(element)) {
How can this happen?

[karlklose, 2013-09-23 08:09:52]

https://codereview.chromium.org/24326003/diff/3001/sdk/lib/_internal/compiler...
File
sdk/lib/_internal/compiler/implementation/dart_backend/placeholder_collector.dart
(right):

https://codereview.chromium.org/24326003/diff/3001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/dart_backend/placeholder_collector.dart:271:
} else if (Elements.isLocal(element) && !isTypedefParameter(element)) {
Typedef parameters are parameters that are not instance members, and not
top-level or static.

[karlklose, 2013-09-24 06:57:01]

Committed patchset #2 manually as r27798 (presubmit successful).