Minor cleanup in resolver_test.dart.

tests/compiler/dart2js/resolver_test.dart

Index: tests/compiler/dart2js/resolver_test.dart
diff --git a/tests/compiler/dart2js/resolver_test.dart b/tests/compiler/dart2js/resolver_test.dart
index 207ffa4488d646e80554efb8c8af1c8ebe4248ae..b05caf550a400c4410a4cb4cedfdcb644dcf49b0 100644
--- a/tests/compiler/dart2js/resolver_test.dart
+++ b/tests/compiler/dart2js/resolver_test.dart
@@ -685,12 +685,7 @@ Future resolveConstructor(
     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,