fixes #276, path manipulation issues on windows. Also fixes server mode

tool/patch_sdk.dart

 #!/usr/bin/env dart
 // Copyright (c) 2015, 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.
 
 /// Command line tool to merge the SDK libraries and our patch files.
 /// This is currently designed as an offline tool, but we could automate it.
 library dev_compiler.tool.patch_sdk;
 
 import 'dart:io';
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:path/path.dart' as path;
 
 void main(List<String> argv) {
   if (argv.length < 2) {
-    var self = path.relative(Platform.script.path);
-    var toolDir = path.relative(path.dirname(Platform.script.path));
+    var self = path.relative(path.fromUri(Platform.script));
+    var toolDir = path.relative(path.dirname(path.fromUri(Platform.script)));
 
     var inputExample = path.join(toolDir, 'input_sdk');
     var outExample = path.relative(
         path.normalize(path.join(toolDir, '..', 'test', 'generated_sdk')));
 
     print('Usage: $self INPUT_DIR OUTPUT_DIR');
     print('For example:');
     print('\$ $self $inputExample $outExample');
 
     inputExample = path.join(toolDir, 'min_sdk');
@@ skipping 362 matching lines @@
     if (diff != 0) return diff;
     return end - other.end;
   }
 }
 
 List<SdkLibrary> _getSdkLibraries(String contents) {
   var libraryBuilder = new SdkLibrariesReader_LibraryBuilder(true);
   parseCompilationUnit(contents).accept(libraryBuilder);
   return libraryBuilder.librariesMap.sdkLibraries;
 }