Backout part of previous commit to fix bots

pkg/analyzer/lib/src/generated/parser.dart

Index: pkg/analyzer/lib/src/generated/parser.dart
diff --git a/pkg/analyzer/lib/src/generated/parser.dart b/pkg/analyzer/lib/src/generated/parser.dart
index 2a0039222a19f6f3601a3f1da83961af52797af7..b8906c16e1f79006bf0d42ab493c05c7b2f21409 100644
--- a/pkg/analyzer/lib/src/generated/parser.dart
+++ b/pkg/analyzer/lib/src/generated/parser.dart
@@ -4152,11 +4152,6 @@ class Parser {
           _tokenMatchesIdentifier(next)) {
         covariantKeyword = getAndAdvance();
       }
-      while (_matchesKeyword(Keyword.COVARIANT)) {
-        _reportErrorForCurrentToken(
-            ParserErrorCode.DUPLICATED_MODIFIER, [_currentToken.lexeme]);
-        _advance();
-      }
     }
     FinalConstVarOrType holder = parseFinalConstVarOrType(!inFunctionType,
         inFunctionType: inFunctionType);