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

sdk/lib/_internal/dartdoc/test/dartdoc_test.dart

 // Copyright (c) 2012, 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.
 
 /// Unit tests for doc.
 library dartdocTests;
 
 import 'dart:async';
 import 'dart:io';
 
@@ skipping 178 matching lines @@
     });
   });
 }
 
 void _testRunDartDoc(List<String> libraryPaths, void eval(ProcessResult)) {
   expect(_runDartdoc(libraryPaths).then(eval), completes);
 }
 
 /// The path to the root directory of the dartdoc entrypoint.
 String get _dartdocDir {
-  var dir = path.absolute(Platform.script);
+  var dir = path.absolute(Platform.script.toFilePath());
   while (path.basename(dir) != 'dartdoc') {
     if (!path.absolute(dir).contains('dartdoc') || dir == path.dirname(dir)) {
       fail('Unable to find root dartdoc directory.');
     }
     dir = path.dirname(dir);
   }
   return path.absolute(dir);
 }
 
 /// The path to use for the package root for subprocesses.
@@ skipping 65 matching lines @@
   }
 }
 
 
 validateDartdocMarkdown(String description, String markdown,
     String html) {
   var dartdoc = new dd.Dartdoc();
   validate(description, markdown, html, linkResolver: dartdoc.dartdocResolver,
       inlineSyntaxes: dartdoc.dartdocSyntaxes);
 }