Add readAsStringSync() to File.

pkg/analyzer/test/file_system/physical_resource_provider_test.dart

 // Copyright (c) 2014, 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.
 
 library test.physical_file_system;
 
 import 'dart:async';
 import 'dart:io' as io;
 
 import 'package:analyzer/file_system/file_system.dart';
@@ skipping 84 matching lines @@
     File file = PhysicalResourceProvider.INSTANCE.getResource(path);
     expect(file.modificationStamp, isNonNegative);
   }
 
   void test_parent() {
     Resource parent = file.parent;
     expect(parent, new isInstanceOf<Folder>());
     expect(parent.path, equals(tempPath));
   }
 
+  void test_readAsStringSync_doesNotExist() {
+    File file = PhysicalResourceProvider.INSTANCE.getResource(path);
+    expect(() {
+      file.readAsStringSync();
+    }, throwsA(_isFileSystemException));
+  }
+
+  void test_readAsStringSync_exists() {
+    new io.File(path).writeAsStringSync('abc');
+    File file = PhysicalResourceProvider.INSTANCE.getResource(path);
+    expect(file.readAsStringSync(), 'abc');
+  }
+
   void test_shortName() {
     expect(file.shortName, 'file.txt');
   }
 
   void test_toString() {
     expect(file.toString(), path);
   }
 }
 
 @reflectiveTest
@@ skipping 258 matching lines @@
 
   setUp() {
     tempDirectory = io.Directory.systemTemp.createTempSync('test_resource');
     tempPath = tempDirectory.absolute.path;
   }
 
   tearDown() {
     tempDirectory.deleteSync(recursive: true);
   }
 }