Remove toplevel inference restriction hints, and restore as much

pkg/analyzer/test/generated/hint_code_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.
 
 library analyzer.test.generated.hint_code_test;
 
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/src/error/codes.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/parser.dart';
@@ skipping 2569 matching lines @@
 main() {
   List dynamicList = [ ];
   List<int> list = dynamicList;
   print(list);
 }''');
     await computeAnalysisResult(source);
     assertErrors(source, [StrongModeCode.DOWN_CAST_COMPOSITE]);
     verify([source]);
   }
 
-  test_strongMode_topLevelInstanceGetter() async {
-    resetWith(options: new AnalysisOptionsImpl()..strongMode = true);
-    Source source = addSource(r'''
-class A {
-  int get g => 0;
-}
-var a = new A();
-var b = a.g;
-''');
-    await computeAnalysisResult(source);
-    assertErrors(source, [StrongModeCode.TOP_LEVEL_INSTANCE_GETTER]);
-    verify([source]);
-  }
-
   test_typeCheck_type_is_Null() async {
     Source source = addSource(r'''
 m(i) {
   bool b = i is Null;
 }''');
     await computeAnalysisResult(source);
     assertErrors(source, [HintCode.TYPE_CHECK_IS_NULL]);
     verify([source]);
   }
 
@@ skipping 1654 matching lines @@
   n() {
     var a = m(), b = m();
   }
 }''');
     await computeAnalysisResult(source);
     assertErrors(
         source, [HintCode.USE_OF_VOID_RESULT, HintCode.USE_OF_VOID_RESULT]);
     verify([source]);
   }
 }