Implement nested switches and missing switch continue targets.

pkg/front_end/lib/src/fasta/testing/kernel_chain.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.md file.
 
 // TODO(ahe): Copied from closure_conversion branch of kernel, remove this file
 // when closure_conversion is merged with master.
 
 library kernel.testing.kernel_chain;
 
 import 'dart:async' show Future;
@@ skipping 174 matching lines @@
 }
 
 class Verify extends Step<Program, Program, TestContext> {
   final bool fullCompile;
 
   const Verify(this.fullCompile);
 
   String get name => "verify";
 
   Future<Result<Program>> run(Program program, TestContext testContext) async {
-    try {
-      verifyProgram(program, isOutline: !fullCompile);
+    var errors = verifyProgram(program, isOutline: !fullCompile);
+    if (errors.isEmpty) {
       return pass(program);
-    } catch (e, s) {
+    } else {
       return new Result<Program>(
-          null, testContext.expectationSet["VerificationError"], e, s);
+          null, testContext.expectationSet["VerificationError"], errors, null);
     }
   }
 }
 
 class MatchExpectation extends Step<Program, Program, TestContext> {
   final String suffix;
 
   // TODO(ahe): This is true by default which doesn't match well with the class
   // name.
   final bool updateExpectations;
@@ skipping 145 matching lines @@
 
 Future openWrite(Uri uri, f(IOSink sink)) async {
   IOSink sink = new File.fromUri(uri).openWrite();
   try {
     await f(sink);
   } finally {
     await sink.close();
   }
   print("Wrote $uri");
 }