Do not error on dead, mandated statements at end of switch cases

pkg/analyzer/test/generated/non_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.non_hint_code_test;
 
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/source_io.dart';
 
 import '../reflective_tests.dart';
@@ skipping 172 matching lines @@
   if (1 < 0) {
     return;
   }
   int a = 1;
 }''');
     computeLibrarySourceErrors(source);
     assertNoErrors(source);
     verify([source]);
   }
 
+  void test_deadCode_deadFinalBreakInCase() {
+    Source source = addSource(r'''
+f() {
+  switch (true) {
+  case true:
+    try {
+      int a = 1;
+    } finally {
+      return;
+    }
+    break;
+  default:
+    break;
+  }
+}''');
+    computeLibrarySourceErrors(source);
+    assertNoErrors(source);
+    verify([source]);
+  }
+
   void test_deprecatedMemberUse_inDeprecatedClass() {
     Source source = addSource(r'''
 @deprecated
 f() {}
 
 @deprecated
 class C {
   m() {
     f();
   }
@@ skipping 1055 matching lines @@
 
   void test_import_valid_outside_lib() {
     cacheSource("/myproj/pubspec.yaml", "");
     cacheSource("/myproj/web/other.dart", "");
     Source source =
         addNamedSource("/myproj/lib2/test.dart", "import '../web/other.dart';");
     computeLibrarySourceErrors(source);
     assertNoErrors(source);
   }
 }