Add data-URI support class to dart:core (next to Uri).

tools/testing/dart/test_suite.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.
 
 /**
  * Classes and methods for enumerating and preparing tests.
  *
  * This library includes:
  *
  * - Creating tests by listing all the Dart files in certain directories,
@@ skipping 206 matching lines @@
     var d8Dir = TestUtils.dartDir.append('third_party/d8');
     var d8Path = d8Dir.append('${Platform.operatingSystem}/d8$suffix');
     var d8 = d8Path.toNativePath();
     TestUtils.ensureExists(d8, configuration);
     return d8;
   }
 
   String get jsShellFileName {
     var executableSuffix = getExecutableSuffix('jsshell');
     var executable = 'jsshell$executableSuffix';
-    var jsshellDir = '${TestUtils.dartDir}/tools/testing/bin';
+    var jsshellDir = '${TestUtils.dartDir.toNativePath()}/tools/testing/bin';
     return '$jsshellDir/$executable';
   }
 
   /**
    * The file extension (if any) that should be added to the given executable
    * name for the current platform.
    */
   // TODO(ahe): Get rid of this. Use executableBinarySuffix instead.
   String getExecutableSuffix(String executable) {
     if (Platform.operatingSystem == 'windows') {
@@ skipping 2182 matching lines @@
       for (var key in PATH_REPLACEMENTS.keys) {
         if (path.startsWith(key)) {
           path = path.replaceFirst(key, PATH_REPLACEMENTS[key]);
           break;
         }
       }
     }
     return path;
   }
 }