Late night strong mode cleaning.

tests/compiler/dart2js/kernel/class_hierarchy_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.
 
 /// Test that the dart2js copy of [KernelVisitor] generates the expected class
 /// hierarchy.
 
 import 'package:compiler/src/commandline_options.dart' show Flags;
 import 'package:compiler/src/compiler.dart' show Compiler;
-import 'package:compiler/src/elements/elements.dart';
 import 'package:compiler/src/js_backend/backend.dart' show JavaScriptBackend;
 import 'package:compiler/src/library_loader.dart' show LoadedLibraries;
 import 'package:kernel/ast.dart' as ir;
 import 'package:kernel/class_hierarchy.dart';
 import 'package:test/test.dart';
 
 import '../memory_compiler.dart';
 
 main(List<String> arguments) {
   Compiler compiler = compilerFor(memorySourceFiles: {
@@ skipping 32 matching lines @@
             print('$cls');
             print(' dispatch targets:');
             hierarchy
                 .getDispatchTargets(cls)
                 .forEach((member) => print('  $member'));
           }
           return cls;
         }
       }
       fail('Class $name not found.');
+      throw "Not reachable.";
     }
 
     ir.Class classS = getClass('S');
     ir.Class classM = getClass('M');
     ir.Class classC = getClass('C');
 
     void checkInheritance(ir.Class superClass, ir.Class subClass) {
       for (ir.Member member in hierarchy.getDispatchTargets(superClass)) {
         expect(
             hierarchy.getDispatchTarget(subClass, member.name), equals(member),
             reason: 'Unexpected dispatch target for ${member.name} '
                 'in $subClass');
       }
     }
 
     checkInheritance(classS, classC);
     checkInheritance(classM, classC);
   });
 }