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

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/src/generated/engine.dart';
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/source_io.dart';
 import 'package:unittest/unittest.dart';
@@ skipping 455 matching lines @@
     case 1:
       break;
       var a;
   }
 }''');
     computeLibrarySourceErrors(source);
     assertErrors(source, [HintCode.DEAD_CODE]);
     verify([source]);
   }
 
+  void test_deadCode_deadFinalReturnInCase() {
+    Source source = addSource(r'''
+f() {
+  switch (true) {
+  case true:
+    try {
+      int a = 1;
+    } finally {
+      return;
+    }
+    return;
+  default:
+    break;
+  }
+}''');
+    computeLibrarySourceErrors(source);
+    assertErrors(source, [HintCode.DEAD_CODE]);
+    verify([source]);
+  }
+
+  void test_deadCode_deadFinalStatementInCase() {
+    Source source = addSource(r'''
+f() {
+  switch (true) {
+  case true:
+    try {
+      int a = 1;
+    } finally {
+      return;
+    }
+    int b = 1;
+  default:
+    break;
+  }
+}''');
+    computeLibrarySourceErrors(source);
+    // A single dead statement at the end of a switch case that is not a
+    // terminating statement will yield two errors.
+    assertErrors(source,
+        [HintCode.DEAD_CODE, StaticWarningCode.CASE_BLOCK_NOT_TERMINATED]);
+    verify([source]);
+  }
+
   void test_deadCode_statementAfterBreak_inWhileStatement() {
     Source source = addSource(r'''
 f(v) {
   while(v) {
     break;
     var a;
   }
 }''');
     computeLibrarySourceErrors(source);
     assertErrors(source, [HintCode.DEAD_CODE]);
@@ skipping 3063 matching lines @@
   n() {
     var a = m(), b = m();
   }
 }''');
     computeLibrarySourceErrors(source);
     assertErrors(
         source, [HintCode.USE_OF_VOID_RESULT, HintCode.USE_OF_VOID_RESULT]);
     verify([source]);
   }
 }