Rename String.concat to operator+.

pkg/intl/lib/bidi_formatter.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.
 
 part of intl;
 
 /**
  * Bidi stands for Bi-directional text.
  * According to [Wikipedia](http://en.wikipedia.org/wiki/Bi-directional_text):
  * Bi-directional text is text containing text in both text directionalities,
@@ skipping 112 matching lines @@
     var directionChange = contextDirection.isDirectionChange(direction);
     if (_alwaysSpan || directionChange) {
       var spanDirection = '';
       if (directionChange) {
         spanDirection = ' dir=${direction.spanText}';
       }
       result= '<span$spanDirection>$text</span>';
     } else {
       result = text;
     }
-    return result.concat(resetDir? _resetDir(text, direction, isHtml) : '');
+    return result + (resetDir? _resetDir(text, direction, isHtml) : '');
   }
 
   /**
    * Format [text] of a known (if specified) or estimated [direction] for use
    * in *plain-text* output of the context directionality, so an
    * opposite-directionality text is neither garbled nor garbles what follows
    * it. Unlike wrapWithSpan, this makes use of unicode BiDi formatting
    * characters instead of spans for wrapping. The returned string would be
    * RLE+text+PDF for RTL text, or LRE+text+PDF for LTR text.
    *
@@ skipping 10 matching lines @@
    */
   String wrapWithUnicode(String text, {bool isHtml: false, bool resetDir: true,
                          TextDirection direction}) {
     if (direction == null) direction = estimateDirection(text, isHtml: isHtml);
     var result = text;
     if (contextDirection.isDirectionChange(direction)) {
       var marker = direction == TextDirection.RTL ? Bidi.RLE : Bidi.LRE;
       result = "${marker}$text${Bidi.PDF}";
 
     }
-    return result.concat(resetDir? _resetDir(text, direction, isHtml) : '');
+    return result + (resetDir? _resetDir(text, direction, isHtml) : '');
   }
 
   /**
    * Estimates the directionality of [text] using the best known
    * general-purpose method (using relative word counts). A
    * TextDirection.UNKNOWN return value indicates completely neutral input.
    * [isHtml] is true if [text] HTML or HTML-escaped.
    */
   TextDirection estimateDirection(String text, {bool isHtml: false}) {
     return Bidi.estimateDirectionOfText(text, isHtml: isHtml); //TODO~!!!
@@ skipping 18 matching lines @@
       if (contextDirection == TextDirection.LTR) {
         return Bidi.LRM;
       } else {
         return Bidi.RLM;
       }
     } else {
       return '';
     }
   }
 }