Report hint when target of an invocation uses '?.', so can be null.

pkg/analyzer/test/generated/resolver_test.dart

 // Copyright (c) 2014, 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 engine.resolver_test;
 
 import 'dart:collection';
 
 import 'package:analyzer/src/context/context.dart' as newContext;
 import 'package:analyzer/src/generated/ast.dart';
@@ skipping 2340 matching lines @@
 m() {
   var i = '';
   n(i);
 }
 n(int i) {}''');
     computeLibrarySourceErrors(source);
     assertErrors(source, [HintCode.ARGUMENT_TYPE_NOT_ASSIGNABLE]);
     verify([source]);
   }
 
+  void test_canBeNullAfterNullAware_methodInvocation() {
+    Source source = addSource(r'''
+m(x) {
+  x?.a.b();
+}
+''');
+    computeLibrarySourceErrors(source);
+    assertErrors(source, [HintCode.CAN_BE_NULL_AFTER_NULL_AWARE]);
+    verify([source]);
+  }
+
+  void test_canBeNullAfterNullAware_parenthesized() {
+    Source source = addSource(r'''
+m(x) {
+  (x?.a).b;
+}
+''');
+    computeLibrarySourceErrors(source);
+    assertErrors(source, [HintCode.CAN_BE_NULL_AFTER_NULL_AWARE]);
+    verify([source]);
+  }
+
+  void test_canBeNullAfterNullAware_propertyAccess() {
+    Source source = addSource(r'''
+m(x) {
+  x?.a.b;
+}
+''');
+    computeLibrarySourceErrors(source);
+    assertErrors(source, [HintCode.CAN_BE_NULL_AFTER_NULL_AWARE]);
+    verify([source]);
+  }
+
   void test_deadCode_deadBlock_conditionalElse() {
     Source source = addSource(r'''
 f() {
   true ? 1 : 2;
 }''');
     computeLibrarySourceErrors(source);
     assertErrors(source, [HintCode.DEAD_CODE]);
     verify([source]);
   }
 
@@ skipping 12658 matching lines @@
 
   void _resolveTestUnit(String code) {
     testCode = code;
     testSource = addSource(testCode);
     LibraryElement library = resolve2(testSource);
     assertNoErrors(testSource);
     verify([testSource]);
     testUnit = resolveCompilationUnit(testSource, library);
   }
 }