Support loading binary data in dart2js

tests/compiler/dart2js/import_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.
 
 // Test that the compiler can handle missing files used in imports, exports,
 // part tags or as the main source file.
 
 library dart2js.test.import;
 
 import 'package:expect/expect.dart';
@@ skipping 53 matching lines @@
     const Expected.info(MessageKind.IMPORT_PART_OF_HERE)
   ]);
 }
 
 testMissingImports() async {
   var collector = new DiagnosticCollector();
   await runCompiler(
       memorySourceFiles: MEMORY_SOURCE_FILES, diagnosticHandler: collector);
 
   collector.checkMessages([
-    const Expected.error(MessageKind.READ_SCRIPT_ERROR),
+    const Expected.error(MessageKind.READ_URI_ERROR),
     const Expected.error(MessageKind.LIBRARY_NOT_FOUND),
     const Expected.error(MessageKind.LIBRARY_NOT_FOUND),
-    const Expected.error(MessageKind.READ_SCRIPT_ERROR),
+    const Expected.error(MessageKind.READ_URI_ERROR),
     const Expected.warning(MessageKind.NOT_ASSIGNABLE)
   ]);
 }
 
 testMissingMain() async {
   var collector = new DiagnosticCollector();
   await runCompiler(
       entryPoint: Uri.parse('memory:missing.dart'),
       diagnosticHandler: collector);
   collector.checkMessages([const Expected.error(MessageKind.READ_SELF_ERROR)]);
 }
 
 void main() {
   asyncTest(() async {
     await testEntryPointIsPart();
     await testImportPart();
     await testMissingImports();
     await testMissingMain();
   });
 }