Make pub warning-clean.

utils/pub/log.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.
 
 /// Message logging.
 library log;
 
 import 'dart:async';
 import 'io.dart';
 
@@ skipping 99 matching lines @@
 /// Logs the spawning of an [executable] process with [arguments] at [IO]
 /// level.
 void process(String executable, List<String> arguments) {
   io("Spawning $executable ${arguments.join(' ')}");
 }
 
 /// Logs the results of running [executable].
 void processResult(String executable, PubProcessResult result) {
   // Log it all as one message so that it shows up as a single unit in the logs.
   var buffer = new StringBuffer();
-  buffer.add("Finished $executable. Exit code ${result.exitCode}.");
+  buffer.write("Finished $executable. Exit code ${result.exitCode}.");
 
   dumpOutput(String name, List<String> output) {
     if (output.length == 0) {
-      buffer.add("Nothing output on $name.");
+      buffer.write("Nothing output on $name.");
     } else {
-      buffer.add("$name:");
+      buffer.write("$name:");
       var numLines = 0;
       for (var line in output) {
         if (++numLines > 1000) {
-          buffer.add('[${output.length - 1000}] more lines of output '
-                     'truncated...]');
+          buffer.write('[${output.length - 1000}] more lines of output '
+              'truncated...]');
           break;
         }
 
-        buffer.add(line);
+        buffer.write(line);
       }
     }
   }
 
   dumpOutput("stdout", result.stdout);
   dumpOutput("stderr", result.stderr);
 
   io(buffer.toString());
 }
 
@@ skipping 73 matching lines @@
         sink.add('    | '.codeUnits);
       }
     }
 
     sink.add(line.codeUnits);
     sink.add('\n'.codeUnits);
 
     firstLine = false;
   }
 }