Reapply "Tweak public APIs and use them in patch_sdk, dart2js, and kernel-service.""

pkg/front_end/lib/src/fasta/parser/dart_vm_native.dart

-// Copyright (c) 2017, 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.
-
-/// Implements support for Dart VM native method bodies of this form:
-///
-///     native STRING
-///
-/// This support is kept separate from parser.dart as this isn't specified in
-/// the Dart Language Specification, also we hope to remove this syntax long
-/// term and replace it with annotations as in `dart2js`.
-library fasta.parser.dart_vm_native;
-
-import '../../scanner/token.dart' show Token;
-
-import '../scanner/token_constants.dart' show STRING_TOKEN;
-
-import '../util/link.dart' show Link;
-
-import 'parser.dart' show optional;
-
-/// When parsing a Dart VM library file, we may encounter a native clause
-/// instead of a function body. This method skips such a clause.
-///
-/// This method is designed to be called when encountering
-/// [ErrorKind.ExpectedBlockToSkip] in [Listener.handleUnrecoverableError].
-Token skipNativeClause(Token token) {
-  if (!optional("native", token)) return null;
-  token = token.next;
-  if (token.kind != STRING_TOKEN) return null;
-  if (!optional(";", token.next)) return null;
-  return token;
-}
-
-/// When parsing a Dart VM library file, we may encounter native getters like
-///
-///     int get length native "List_getLength";
-///
-/// This will result in [identifiers] being
-///
-///     [";", '"List_getLength"', "native", "length", "get"]
-///
-/// We need to remove '"List_getLength"' and "native" from that list.
-///
-/// This method designed to be called from [Listener.handleMemberName].
-Link<Token> removeNativeClause(Link<Token> identifiers) {
-  Link<Token> result = identifiers.tail;
-  if (result.isEmpty) return identifiers;
-  if (result.head.kind != STRING_TOKEN) return identifiers;
-  result = result.tail;
-  if (result.isEmpty) return identifiers;
-  if (optional('native', result.head)) {
-    return result.tail.prepend(identifiers.head);
-  }
-  return identifiers;
-}