Fix use of string buffer in pathos

pkg/pathos/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.
 library path;
 
 import 'dart:io' as io;
 
 /// An internal builder for the current OS so we can provide a straight
@@ skipping 176 matching lines @@
     // Ignore nulls hanging off the end.
     if (args[i] == null || args[i - 1] != null) continue;
 
     var numArgs;
     for (numArgs = args.length; numArgs >= 1; numArgs--) {
       if (args[numArgs - 1] != null) break;
     }
 
     // Show the arguments.
     var message = new StringBuffer();
-    message.add("$method(");
-    message.add(args.take(numArgs)
+    message.write("$method(");
+    message.write(args.take(numArgs)
         .map((arg) => arg == null ? "null" : '"$arg"')
         .join(", "));
-    message.add("): part ${i - 1} was null, but part $i was not.");
+    message.write("): part ${i - 1} was null, but part $i was not.");
     throw new ArgumentError(message.toString());
   }
 }
 
 /// An instantiable class for manipulating paths. Unlike the top-level
 /// functions, this lets you explicitly select what platform the paths will use.
 class Builder {
   /// Creates a new path builder for the given style and root directory.
   ///
   /// If [style] is omitted, it uses the host operating system's path style. If
@@ skipping 145 matching lines @@
   ///     builder.joinAll(['path', '/to', 'foo']); // -> '/to/foo'
   ///
   /// For a fixed number of parts, [join] is usually terser.
   String joinAll(Iterable<String> parts) {
     var buffer = new StringBuffer();
     var needsSeparator = false;
 
     for (var part in parts) {
       if (this.isAbsolute(part)) {
         // An absolute path discards everything before it.
-        buffer.clear();
-        buffer.add(part);
+        buffer = new StringBuffer();
+        buffer.write(part);
       } else {
         if (part.length > 0 && part[0].contains(style.separatorPattern)) {
           // The part starts with a separator, so we don't need to add one.
         } else if (needsSeparator) {
-          buffer.add(separator);
+          buffer.write(separator);
         }
 
-        buffer.add(part);
+        buffer.write(part);
       }
 
       // Unless this part ends with a separator, we'll need to add one before
       // the next part.
       needsSeparator = part.length > 0 &&
           !part[part.length - 1].contains(style.separatorPattern);
     }
 
     return buffer.toString();
   }
@@ skipping 307 matching lines @@
 
     // Normalize the Windows root if needed.
     if (root != null && style == Style.windows) {
       root = root.replaceAll('/', '\\');
     }
     removeTrailingSeparators();
   }
 
   String toString() {
     var builder = new StringBuffer();
-    if (root != null) builder.add(root);
+    if (root != null) builder.write(root);
     for (var i = 0; i < parts.length; i++) {
-      builder.add(parts[i]);
-      builder.add(separators[i]);
+      builder.write(parts[i]);
+      builder.write(separators[i]);
     }
 
     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.
   List<String> _splitExtension() {
     if (parts.isEmpty) return ['', ''];
 
     var file = parts.last;
     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, new List.from(parts), new List.from(separators));
 }