add support for native methods in class

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 589b785bc1a09b9aafdca860fc4f7ee221d3bcae..5873b9095b15f9eb2583f5edfd9ff37b5b4759d1 100644
--- a/pkg/analyzer/test/generated/parser_test.dart
+++ b/pkg/analyzer/test/generated/parser_test.dart
@@ -940,11 +940,18 @@ void Function<A>(core.List<core.int> x) m() => null;
   void test_parseClassMember_method_native() {
     createParser('m() native "str";');
     var method = parser.parseClassMember('C') as MethodDeclaration;
-    assertNoErrors();
+    if (!allowNativeClause) {
+      assertErrorsWithCodes([
+        ParserErrorCode.NATIVE_CLAUSE_SHOULD_BE_ANNOTATION,
+      ]);
+    } else {
+      assertNoErrors();
+    }
 
     var body = method.body as NativeFunctionBody;
     expect(body.nativeKeyword, isNotNull);
     expect(body.stringLiteral, isNotNull);
+    expect(body.stringLiteral?.stringValue, "str");
     expect(body.semicolon, isNotNull);
   }