Introduces the new syntax for deferred loading

tests/compiler/dart2js/unparser_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 'parser_helper.dart';
 import 'mock_compiler.dart';
 import '../../../sdk/lib/_internal/compiler/implementation/tree/tree.dart';
 
 testUnparse(String statement) {
@@ skipping 185 matching lines @@
   testUnparseTopLevelWithMetadata('export "søhest" show a,hide show a,hide;');
   testUnparseTopLevelWithMetadata('export "søhest" show a,show show a,show;');
 
   testUnparseTopLevelWithMetadata('export "søhest" hide a hide a;');
   testUnparseTopLevelWithMetadata('export "søhest" hide hide hide hide;');
   testUnparseTopLevelWithMetadata('export "søhest" hide show hide show;');
   testUnparseTopLevelWithMetadata('export "søhest" hide a,hide hide a,hide;');
   testUnparseTopLevelWithMetadata('export "søhest" hide a,show hide a,show;');
 }
 
+testDeferredImport() {
+  testUnparseTopLevelWithMetadata('import "lib.dart" as a;');
+  testUnparseTopLevelWithMetadata('import "lib.dart" deferred as a;');
+  testUnparseTopLevelWithMetadata('import "lib.dart" deferred as a show b;');
+  testUnparseTopLevelWithMetadata('import "lib.dart" deferred as a hide b;');
+}
+
 testUnparseMemberAndAsMemberOfFoo(String code) {
   testUnparseMember(code);
   testUnparseTopLevelWithMetadata('class Foo{$code}');
 }
 
 testRedirectingFactoryConstructors() {
   testUnparseMemberAndAsMemberOfFoo("factory Foo() = Bar;");
   testUnparseMemberAndAsMemberOfFoo("factory Foo() = Bar.baz;");
   testUnparseMemberAndAsMemberOfFoo("factory Foo() = Bar<T>;");
   testUnparseMemberAndAsMemberOfFoo("factory Foo() = Bar<List<T>,T>;");
@@ skipping 157 matching lines @@
   testNativeMethods();
   testPrefixIncrements();
   testConstModifier();
   testSimpleObjectInstantiation();
   testLibraryName();
   testImport();
   testExport();
   testPart();
   testPartOf();
   testCombinators();
+  testDeferredImport();
   testRedirectingFactoryConstructors();
   testClassDeclarations();
   testMixinApplications();
   testParameters();
   testSymbolLiterals();
 }