[cfe] Ignore context when de-duplicating error messages

Change-Id: I44b00ca5277f69fdaa05bb71a5409ea9dabac601
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/121061
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Commit-Queue: Aske Simon Christensen <askesc@google.com>

Author: askeksa

pkg/front_end/lib/src/fasta/loader.dart

@@ -314,17 +314,6 @@ charOffset: $charOffset
 fileUri: $fileUri
 severity: $severity
 """;
-    // TODO(askesc): Swap message and context around for interface checks
-    // and mixin overrides to make comparing context here unnecessary.
-    if (context != null) {
-      for (LocatedMessage contextMessage in context) {
-        trace += """
-message: ${contextMessage.message}
-charOffset: ${contextMessage.charOffset}
-fileUri: ${contextMessage.uri}
-""";
-      }
-    }
     if (!seenMessages.add(trace)) return null;
     if (message.code.severity == Severity.context) {
       internalProblem(

pkg/front_end/testcases/general/duplicated_declarations.dart.outline.expect

@@ -306,10 +306,6 @@ library;
 // class Sub extends C {
 //                   ^
 //
-// pkg/front_end/testcases/general/duplicated_declarations.dart:65:19: Error: 'C' isn't a type.
-// class Sub extends C {
-//                   ^
-//
 import self as self;
 import "dart:core" as core;
 

pkg/front_end/testcases/general/duplicated_declarations.dart.strong.expect

@@ -306,10 +306,6 @@ library;
 // class Sub extends C {
 //                   ^
 //
-// pkg/front_end/testcases/general/duplicated_declarations.dart:65:19: Error: 'C' isn't a type.
-// class Sub extends C {
-//                   ^
-//
 // pkg/front_end/testcases/general/duplicated_declarations.dart:34:3: Error: Can't use 'main' because it is declared more than once.
 //   main();
 //   ^