Fix more tests on windows bots

pkg/analyzer/test/src/source/source_resource_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.
 
 library analyzer.test.src.source.source_resource_test;
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analyzer/file_system/physical_file_system.dart';
 import 'package:analyzer/src/generated/java_engine_io.dart';
@@ skipping 75 matching lines @@
     expect(FileSource.fileReadMode('\r'), '\n');
     expect(FileSource.fileReadMode('a\r'), 'a\n');
     expect(FileSource.fileReadMode('\ra'), '\na');
 
     FileSource.fileReadMode = (String s) => s;
   }
 
   void test_getEncoding() {
     SourceFactory factory =
         new SourceFactory([new ResourceUriResolver(resourceProvider)]);
-    String fullPath = "/does/not/exist.dart";
+    String fullPath = resourceProvider.convertPath("/does/not/exist.dart");
     File file = resourceProvider.getFile(fullPath);
     FileSource source = new FileSource(file);
     expect(factory.fromEncoding(source.encoding), source);
   }
 
   void test_getFullName() {
     String fullPath = "/does/not/exist.dart";
     File file = resourceProvider.getFile(fullPath);
     FileSource source = new FileSource(file);
     expect(source.fullName, file.path);
@@ skipping 92 matching lines @@
     FileSource source = new FileSource(file, Uri.parse("dart:core"));
     expect(source, isNotNull);
     expect(source.fullName, file.path);
     expect(source.isInSystemLibrary, isTrue);
   }
 
   DartSdk _createSdk() {
     return new MockSdk(resourceProvider: resourceProvider);
   }
 }