Minor cleanup in resolver_test.dart.

tests/compiler/dart2js/resolver_test.dart

 // Copyright (c) 2012, 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 'dart:async';
 import "package:async_helper/async_helper.dart";
 import 'dart:collection';
 
 import "package:compiler/src/resolution/resolution.dart";
@@ skipping 667 matching lines @@
     {List expectedWarnings: const [],
      List expectedErrors: const [],
      List expectedInfos: const [],
      Map<String, String> corelib}) {
   MockCompiler compiler = new MockCompiler.internal(coreSource: corelib);
   return compiler.init().then((_) {
     compiler.parseScript(script);
     compiler.resolveStatement(statement);
     ClassElement classElement = compiler.mainApp.find(className);
     Element element;
-    if (constructor != '') {
-      element = classElement.lookupConstructor(constructor);
-    } else {
-      element = classElement.lookupDefaultConstructor();
-    }
-
+    element = classElement.lookupConstructor(constructor);
     FunctionExpression tree = (element as FunctionElement).node;
     ResolverVisitor visitor =
         new ResolverVisitor(compiler, element,
             new ResolutionRegistry.internal(compiler,
                 new CollectingTreeElements(element)));
     new InitializerResolver(visitor).resolveInitializers(element, tree);
     visitor.visit(tree.body);
     Expect.equals(expectedElementCount, map(visitor).length);
 
     compareWarningKinds(script, expectedWarnings, compiler.warnings);
@@ skipping 436 matching lines @@
       }""";
   asyncTest(() => compileScript(script2).then((compiler) {
     expect(compiler,
         [MessageKind.CONST_CONSTRUCTOR_WITH_NONFINAL_FIELDS],
         [MessageKind.CONST_CONSTRUCTOR_WITH_NONFINAL_FIELDS_CONSTRUCTOR,
          MessageKind.CONST_CONSTRUCTOR_WITH_NONFINAL_FIELDS_CONSTRUCTOR,
          MessageKind.CONST_CONSTRUCTOR_WITH_NONFINAL_FIELDS_FIELD,
          MessageKind.CONST_CONSTRUCTOR_WITH_NONFINAL_FIELDS_FIELD]);
   }));
 }