Support --use-kernel in memory_compiler

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/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: {
-    'main.dart': '''
-      class S {
-        sMethod() {}
-      }
-      class M {
-        mMethod() {}
-      }
-      class C extends S with M {
-        cMethod() {}
-      }
-      main() {}
-      '''
-  }, options: [
-    Flags.analyzeOnly,
-    Flags.analyzeAll,
-    Flags.useKernelInSsa
-  ]);
-  test('mixin', () async {
-    Uri mainUri = Uri.parse('memory:main.dart');
-    await compiler.run(mainUri);
-    LoadedLibraries libraries =
-        await compiler.libraryLoader.loadLibrary(mainUri);
-    compiler.processLoadedLibraries(libraries);
-    JavaScriptBackend backend = compiler.backend;
-    ir.Program program = backend.kernelTask.buildProgram(libraries.rootLibrary);
-    ClosedWorldClassHierarchy hierarchy =
-        new ClosedWorldClassHierarchy(program);
-
-    ir.Class getClass(String name) {
-      for (ir.Class cls in hierarchy.classes) {
-        if (cls.enclosingLibrary.importUri == mainUri && cls.name == name) {
-          if (arguments.contains('-v')) {
-            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);
-  });
-}