Fix the merge of locals handler logic.

tests/compiler/dart2js/simple_inferrer_test.dart

 // Copyright (c) 2013, 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.
 
 import 'package:expect/expect.dart';
 import "package:async_helper/async_helper.dart";
 import
     '../../../sdk/lib/_internal/compiler/implementation/types/types.dart'
     show TypeMask;
 
@@ skipping 658 matching lines @@
     checkReturn('testBreak1', interceptorType.nullable());
     checkReturn('testContinue2', interceptorType.nullable());
     checkReturn('testBreak2', typesTask.intType.nullable());
     checkReturn('testReturnElementOfConstList1', typesTask.intType);
     checkReturn('testReturnElementOfConstList2', typesTask.intType);
     checkReturn('testReturnItselfOrInt', typesTask.intType);
     checkReturn('testReturnInvokeDynamicGetter', typesTask.dynamicType);
 
     checkReturn('testDoWhile1', typesTask.stringType);
     checkReturn('testDoWhile2', typesTask.nullType);
-    checkReturn('testDoWhile3', interceptorType);
+    checkReturn('testDoWhile3', typesTask.intType);
     checkReturn('testDoWhile4', typesTask.numType);
 
     checkReturnInClass(String className, String methodName, type) {
       var cls = findElement(compiler, className);
       var element = cls.lookupLocalMember(buildSourceString(methodName));
       Expect.equals(type,
           typesInferrer.getReturnTypeOfElement(element).simplify(compiler));
     }
 
     checkReturnInClass('A', 'returnInt1', typesTask.intType);
@@ skipping 23 matching lines @@
     checkFactoryConstructor('A', '');
 
     checkReturn('testCascade1', typesTask.growableListType);
     checkReturn('testCascade2', new TypeMask.nonNullExact(
         typesTask.rawTypeOf(findElement(compiler, 'CascadeHelper'))));
     checkReturn('testSpecialization1', typesTask.numType);
     checkReturn('testSpecialization2', typesTask.dynamicType);
     checkReturn('testSpecialization3', typesTask.intType.nullable());
   }));
 }