Less inequivalence on Hello World!

tests/compiler/dart2js/kernel/compile_from_dill_test.dart

 // Copyright (c) 2017, 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.
 
 // Partial test that the closed world computed from [WorldImpact]s derived from
 // kernel is equivalent to the original computed from resolution.
 library dart2js.kernel.compile_from_dill_test;
 
 import 'dart:async';
 import 'dart:io';
@@ skipping 157 matching lines @@
   print('--- checking codegen enqueuers--------------------------------------');
   checkCodegenEnqueuers(compiler1.enqueuer.codegenEnqueuerForTesting,
       compiler2.enqueuer.codegenEnqueuerForTesting,
       elementEquivalence: (a, b) => equivalence.entityEquivalence(a, b),
       typeEquivalence: (DartType a, DartType b) {
         return equivalence.typeEquivalence(unalias(a), b);
       },
       elementFilter: elementFilter,
       verbose: arguments.verbose);
 
+  checkEmitters(compiler1.backend.emitter, compiler2.backend.emitter,
+      elementEquivalence: (a, b) => equivalence.entityEquivalence(a, b),
+      typeEquivalence: (DartType a, DartType b) {
+        return equivalence.typeEquivalence(unalias(a), b);
+      },
+      verbose: arguments.verbose);
+
   print('--- checking output------- -----------------------------------------');
   collector1.outputMap
       .forEach((OutputType outputType, Map<String, BufferedOutputSink> map1) {
     if (outputType == OutputType.sourceMap) {
       // TODO(johnniwinther): Support source map from .dill.
       return;
     }
     Map<String, BufferedOutputSink> map2 = collector2.outputMap[outputType];
     checkSets(map1.keys, map2.keys, 'output', equality);
     map1.forEach((String name, BufferedOutputSink output1) {
       BufferedOutputSink output2 = map2[name];
       Expect.stringEquals(output1.text, output2.text);
     });
   });
   return ResultKind.success;
 }