Ignore all trailing separators in path.extension.

pkg/path/lib/path.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.
 
 /// A comprehensive, cross-platform path manipulation library.
 ///
 /// ## Installing ##
 ///
 /// Use [pub][] to install this package. Add the following to your
 /// `pubspec.yaml` file.
@@ skipping 1025 matching lines @@
   /// directories.
   List<String> parts;
 
   /// The path separators preceding each part.
   ///
   /// The first one will be an empty string unless the root requires a separator
   /// between it and the path. The last one will be an empty string unless the
   /// path ends with a trailing separator.
   List<String> separators;
 
-  /// The file extension of the last part, or "" if it doesn't have one.
+  /// The file extension of the last non-empty part, or "" if it doesn't have
+  /// one.
   String get extension => _splitExtension()[1];
 
   /// `true` if this is an absolute path.
   bool get isAbsolute => root != null;
 
   _ParsedPath(this.style, this.root, this.isRootRelative, this.parts,
       this.separators);
 
   String get basename {
     var copy = this.clone();
     copy.removeTrailingSeparators();
     if (copy.parts.isEmpty) return root == null ? '' : root;
     return copy.parts.last;
   }
 
-  String get basenameWithoutExtension {
-    var copy = this.clone();
-    copy.removeTrailingSeparators();
-    if (copy.parts.isEmpty) return root == null ? '' : root;
-    return copy._splitExtension()[0];
-  }
+  String get basenameWithoutExtension => _splitExtension()[0];
 
   bool get hasTrailingSeparator =>
       !parts.isEmpty && (parts.last == '' || separators.last != '');
 
   void removeTrailingSeparators() {
     while (!parts.isEmpty && parts.last == '') {
       parts.removeLast();
       separators.removeLast();
     }
     if (separators.length > 0) separators[separators.length - 1] = '';
@@ skipping 52 matching lines @@
     if (root != null) builder.write(root);
     for (var i = 0; i < parts.length; i++) {
       builder.write(separators[i]);
       builder.write(parts[i]);
     }
     builder.write(separators.last);
 
     return builder.toString();
   }
 
-  /// Splits the last part of the path into a two-element list. The first is
-  /// the name of the file without any extension. The second is the extension
-  /// or "" if it has none.
+  /// Splits the last non-empty part of the path into a `[basename, extension`]
+  /// pair.
+  ///
+  /// Returns a two-element list. The first is the name of the file without any
+  /// extension. The second is the extension or "" if it has none.
   List<String> _splitExtension() {
-    if (parts.isEmpty) return ['', ''];
+    var file = parts.lastWhere((p) => p != '', orElse: () => null);
 
-    var file = parts.last;
+    if (file == null) return ['', ''];
     if (file == '..') return ['..', ''];
 
     var lastDot = file.lastIndexOf('.');
 
     // If there is no dot, or it's the first character, like '.bashrc', it
     // doesn't count.
     if (lastDot <= 0) return [file, ''];
 
     return [file.substring(0, lastDot), file.substring(lastDot)];
   }
 
   _ParsedPath clone() => new _ParsedPath(
       style, root, isRootRelative,
       new List.from(parts), new List.from(separators));
 }