Allow new public names in patches for the dart:_internal library.

pkg/analyzer/test/src/dart/sdk/patch_test.dart

 // Copyright (c) 2016, 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.
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analyzer/src/dart/sdk/patch.dart';
 import 'package:analyzer/src/dart/sdk/sdk.dart';
@@ skipping 261 matching lines @@
           r'''
 @patch
 class A {
   @patch
   int b;
 }
 ''');
     }, throwsArgumentError);
   }
 
-  test_class_field_append_publiInPrivateClass() {
+  test_class_field_append_publicInPrivateClass() {
     CompilationUnit unit = _doTopLevelPatching(
         r'''
 class _C {
   void a() {}
 }
 ''',
         r'''
 @patch
 class _C {
   int b = 42;
@@ skipping 180 matching lines @@
     patches: {VM_PLATFORM: ['does_not_exists.dart']}),
 };''');
       _createSdk();
       File file = provider.newFile(_p('/sdk/lib/test/test.dart'), '');
       Source source = file.createSource(FastUri.parse('dart:test'));
       CompilationUnit unit = SdkPatcher.parse(source, true, listener);
       patcher.patch(sdk, SdkLibraryImpl.VM_PLATFORM, listener, source, unit);
     }, throwsArgumentError);
   }
 
+  test_internal_allowNewPublicNames() {
+    _setSdkLibraries(r'''
+final Map<String, LibraryInfo> LIBRARIES = const <String, LibraryInfo> {
+  '_internal' : const LibraryInfo(
+    'internal/internal.dart',
+    patches: {VM_PLATFORM: ['internal/internal_patch.dart']}),
+};''');
+    File file = provider.newFile(
+        _p('/sdk/lib/internal/internal.dart'),
+        r'''
+library dart._internal;
+class A {}
+class B {
+  B();
+}
+''');
+    provider.newFile(
+        _p('/sdk/lib/internal/internal_patch.dart'),
+        r'''
+@patch
+class B {
+  int newField;
+  B.newConstructor();
+  int newMethod() => 1;
+}
+class NewClass {}
+int newFunction() => 2;
+''');
+
+    _createSdk();
+
+    Source source = file.createSource(FastUri.parse('dart:_internal'));
+    CompilationUnit unit = SdkPatcher.parse(source, true, listener);
+    patcher.patch(sdk, SdkLibraryImpl.VM_PLATFORM, listener, source, unit);
+    _assertUnitCode(
+        unit,
+        'library dart._internal; class A {} '
+        'class B {B(); int newField; B.newConstructor(); int newMethod() => 1;} '
+        'class NewClass {} int newFunction() => 2;');
+  }
+
   test_part() {
     String baseLibCode = r'''
 library test;
 part 'test_part.dart';
 class A {}
 ''';
     String basePartCode = r'''
 part of test;
 class B {}
 ''';
@@ skipping 294 matching lines @@
   void _setSdkLibraries(String code) {
     provider.newFile(
         _p('/sdk/lib/_internal/sdk_library_metadata/lib/libraries.dart'), code);
   }
 
   static void _assertPrevNextToken(Token prev, Token next) {
     expect(prev.next, same(next));
     expect(next.previous, same(prev));
   }
 }