Add `=` as default-value separator for named parameters.

pkg/analyzer/test/generated/parser_test.dart

Index: pkg/analyzer/test/generated/parser_test.dart
diff --git a/pkg/analyzer/test/generated/parser_test.dart b/pkg/analyzer/test/generated/parser_test.dart
index 0fbcf0849569cc21a04e0a24c829277455239944..2e46dfeb9b967abfa0e97e1a57066e3ab807dbeb 100644
--- a/pkg/analyzer/test/generated/parser_test.dart
+++ b/pkg/analyzer/test/generated/parser_test.dart
@@ -2770,14 +2770,6 @@ void main() {
     listener.assertErrorsWithCodes([ParserErrorCode.WITH_WITHOUT_EXTENDS]);
   }
 
-  void test_wrongSeparatorForNamedParameter() {
-    createParser('(a, {b = 0})');
-    FormalParameterList list = parser.parseFormalParameterList();
-    expectNotNullIfNoErrors(list);
-    listener.assertErrorsWithCodes(
-        [ParserErrorCode.WRONG_SEPARATOR_FOR_NAMED_PARAMETER]);
-  }
-
   void test_wrongSeparatorForPositionalParameter() {
     createParser('(a, [b : 0])');
     FormalParameterList list = parser.parseFormalParameterList();