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

tests/co19/co19-dart2js.status

 # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 [ $compiler == dart2js && $runtime == drt ]
 LibTest/core/List/sort_A01_t02: Pass, Fail # v8 bug: Issue 12293
 LibTest/core/List/sort_A01_t03: Pass, Fail # v8 bug: Issue 12293
 LibTest/core/Map/Map_class_A01_t04: Pass, Fail # v8 bug: Issue 12293
 
 [ $compiler == dart2js && $runtime == jsshell ]
@@ skipping 156 matching lines @@
 
 
 #
 # Issues with co19 test suite.
 #
 # If you add anything here, either file a bug against the Dart
 # language specification, co19 test suite, or add a comment that ahe@
 # can understand so he can file a bug later.
 #
 [ $compiler == dart2js ]
-Language/03_Overview/1_Scoping_A01_t40: Fail, OK # co19 issue 188
-Language/03_Overview/1_Scoping_A01_t41: Fail, OK # co19 issue 188
 Language/03_Overview/2_Privacy_A01_t09: Fail, OK # co19 issue 198
 Language/03_Overview/2_Privacy_A01_t11: Pass, OK # co19 issue 316
 Language/06_Functions/4_External_Functions_A01_t01: Fail, OK # http://dartbug.com/5021
 LibTest/core/int/hashCode_A01_t01: Fail, OK # co19 issue 308
 LibTest/typed_data/Int64List/*: Fail # co19-roll r559: Please triage this failure
 LibTest/typed_data/Int64List/Int64List_A02_t01: pass # co19-roll r559: Please triage this failure
 LibTest/typed_data/Uint64List/*: Fail # co19-roll r559: Please triage this failure
 LibTest/typed_data/Uint64List/Uint64List_A02_t01: pass # co19-roll r559: Please triage this failure
 LibTest/typed_data/ByteData/*Uint64*: fail # co19-roll r569: Please triage this failure
 LibTest/typed_data/ByteData/*Int64*: fail # co19-roll r569: Please triage this failure
@@ skipping 91 matching lines @@
 LibTest/core/RegExp/Pattern_semantics/firstMatch_NonEmptyClassRanges_A01_t05: Fail # Expect.fail('Some exception expected')
 LibTest/core/RegExp/Pattern_semantics/firstMatch_NonEmptyClassRanges_A01_t06: Fail # Expect.fail('Some exception expected')
 
 [ $compiler == dart2js && ($runtime == ie10 || $runtime == ff || $runtime == chrome || $runtime == drt || $runtime == safari || $runtime == opera) ]
 *: Skip
 
 #
 # Missing compile-time errors.
 #
 [ $compiler == dart2js ]
-Language/03_Overview/1_Scoping_A01_t39: Fail # dartbug.com/7202
 Language/05_Variables/05_Variables_A01_t04: Fail # Checks that a variable declaration cannot contain both 'final' and 'var'.
 Language/05_Variables/05_Variables_A01_t05: Fail # Checks that a variable declaration cannot contain both 'var' and 'type'.
 Language/05_Variables/05_Variables_A01_t08: Fail # Checks different variables in a single variable declaration must be delimited by commas.
 Language/05_Variables/05_Variables_A01_t12: Fail # Checks that variable declaration cannot contain both 'const' and 'var'.
 Language/05_Variables/05_Variables_A01_t13: Fail # Checks that variable declaration cannot contain both 'const' and 'final'.
 Language/05_Variables/05_Variables_A01_t14: Fail # Checks that variable declaration cannot contain 'const', 'final' and 'var' simultaneously.
 Language/05_Variables/05_Variables_A07_t05: Fail # Checks that a compile-time error occurs if a local constant variable is not initialized at declaration.
 Language/05_Variables/05_Variables_A07_t06: Fail # Checks that a compile-time error occurs if a local typed constant variable is not initialized at declaration.
 Language/05_Variables/05_Variables_A07_t07: Fail # Checks that a compile-time error occurs if a global constant variable is not initialized at declaration.
 Language/05_Variables/05_Variables_A07_t08: Fail # Checks that a compile-time error occurs if a global typed constant variable is not initialized at declaration.
@@ skipping 356 matching lines @@
 LibTest/typed_data/Uint32List/runtimeType_A01_t01: fail # co19-roll r559: Please triage this failure
 LibTest/typed_data/Uint8ClampedList/runtimeType_A01_t01: fail # co19-roll r559: Please triage this failure
 LibTest/typed_data/Uint8List/runtimeType_A01_t01: fail # co19-roll r559: Please triage this failure
 
 [ $compiler == dart2js || $compiler == dart2dart ]
 Language/07_Classes/6_Constructors/1_Generative_Constructors_A15_t08: fail # co19-roll r569: Please triage this failure
 LibTest/core/NoSuchMethodError/NoSuchMethodError_A01_t01: fail # co19-roll r576: Please triage this failure
 LibTest/core/Uri/Uri_A06_t02: fail # co19-roll r576: Please triage this failure
 LibTest/core/Uri/Uri_A06_t03: fail # co19-roll r576: Please triage this failure