Support loading binary data in dart2js

tests/compiler/dart2js/library_env_test.dart

 // Copyright (c) 2016, 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.
 
 /// Check that 'dart:' libraries have their corresponding dart.library.X
 /// environment variable set.
 
-import "memory_source_file_helper.dart";
+import 'dart:async';
+
+import 'memory_source_file_helper.dart';
 
 import "package:async_helper/async_helper.dart";
 
 import 'package:expect/expect.dart' show Expect;
 
 import 'package:compiler/src/null_compiler_output.dart' show NullCompilerOutput;
 
 import 'package:compiler/src/options.dart' show CompilerOptions;
 
+import 'package:compiler/src/io/source_file.dart' show Binary;
+
 import 'package:compiler/compiler_new.dart'
-    show CompilerInput, CompilerDiagnostics;
+    show CompilerInput, CompilerDiagnostics, Input, InputKind;
 
-const clientPlatform = r'''
+const String clientPlatform = r'''
 [dart-spec]
 spec: 3rd edition.
 
 [features]
 # No extra features
 
 [libraries]
 mock.client: mock1.dart
 mock.shared: mock3.dart
 collection: collection/collection.dart
 html: html/dart2js/html_dart2js.dart
 ''';
 
-const serverPlatform = r'''
+const String serverPlatform = r'''
 [dart-spec]
 spec: 3rd edition.
 
 [features]
 # No extra features
 
 [libraries]
 mock.server: mock2.dart
 mock.shared: mock3.dart
 collection: collection/collection.dart
 io: io/io.dart
 ''';
 
 class DummyCompilerInput implements CompilerInput {
   const DummyCompilerInput();
 
-  readFromUri(uri) async {
+  Future<Input> readFromUri(Uri uri,
+      {InputKind inputKind: InputKind.utf8}) async {
     if (uri.toString().endsWith("dart_client.platform")) {
-      return clientPlatform;
+      return new Binary(uri, clientPlatform.codeUnits);
     } else if (uri.toString().endsWith("dart_server.platform")) {
-      return serverPlatform;
+      return new Binary(uri, serverPlatform.codeUnits);
     } else {
       throw "should not be needed $uri";
     }
   }
 }
 
 class DummyCompilerDiagnostics implements CompilerDiagnostics {
   const DummyCompilerDiagnostics();
 
   report(code, uri, begin, end, text, kind) {
@@ skipping 57 matching lines @@
   Expect.equals("false", compiler.fromEnvironment("dart.library.collection"));
   Expect.equals("foo", compiler.fromEnvironment("dart.library.mock.client"));
 }
 
 main() {
   asyncStart();
   runTest().then((_) {
     asyncEnd();
   });
 }