Change dart:io Platform.script to return a Uri.

sdk/lib/_internal/pub/lib/src/io.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.
 
 /// Helper functionality to make working with IO easier.
 library pub.io;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
@@ skipping 363 matching lines @@
   // directory since it may just be a leaf application that only has
   // code in bin or web.
   if (!isSelfLink) {
     log.warning('Warning: Package "$name" does not have a "lib" directory so '
                 'you will not be able to import any libraries from it.');
   }
 }
 
 /// Whether pub is running from within the Dart SDK, as opposed to from the Dart
 /// source repository.
-bool get runningFromSdk => path.extension(Platform.script) == '.snapshot';
+bool get runningFromSdk => Platform.script.path.endsWith('.snapshot');
 
 /// Resolves [target] relative to the path to pub's `resource` directory.
 String resourcePath(String target) {
   if (runningFromSdk) {
     return path.join(
         sdk.rootDirectory, 'lib', '_internal', 'pub', 'resource', target);
   } else {
     return path.join(
         path.dirname(libraryPath('pub.io')), '..', '..', 'resource', target);
   }
@@ skipping 439 matching lines @@
   const PubProcessResult(this.stdout, this.stderr, this.exitCode);
 
   bool get success => exitCode == 0;
 }
 
 /// Gets a [Uri] for [uri], which can either already be one, or be a [String].
 Uri _getUri(uri) {
   if (uri is Uri) return uri;
   return Uri.parse(uri);
 }