[dart:io] Move _getUriBaseClosure to dart:io

runtime/bin/directory_patch.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.
 
 @patch
 class _Directory {
   @patch
   static _current() native "Directory_Current";
   @patch
   static _setCurrent(path) native "Directory_SetCurrent";
@@ skipping 28 matching lines @@
     implements _AsyncDirectoryListerOps {
   _AsyncDirectoryListerOpsImpl._();
 
   factory _AsyncDirectoryListerOpsImpl(int pointer) =>
       new _AsyncDirectoryListerOpsImpl._().._setPointer(pointer);
 
   void _setPointer(int pointer)
       native "Directory_SetAsyncDirectoryListerPointer";
   int getPointer() native "Directory_GetAsyncDirectoryListerPointer";
 }
+
+// Corelib 'Uri.base' implementation.
+// Uri.base is susceptible to changes in the current working directory.
+Uri _uriBaseClosure() {
+  var result = _Directory._current();
+  if (result is OSError) {
+    throw new FileSystemException(
+        "Getting current working directory failed", "", result);
+  }
+  return new Uri.directory(result);
+}
+
+_getUriBaseClosure() => _uriBaseClosure;