- Remove String + operator in uri.dart.

lib/uri/uri.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.
 
 #library('uri');
 
 /**
  * A parsed URI, inspired by:
  * http://closure-library.googlecode.com/svn/docs/class_goog_Uri.html
  */
@@ skipping 26 matching lines @@
   static int _parseIntOrZero(String val) {
     if (val !== null && val != '') {
       return Math.parseInt(val);
     } else {
       return 0;
     }
   }
 
   // NOTE: This code was ported from: closure-library/closure/goog/uri/utils.js
   static final RegExp _splitRe = const RegExp(
-      '^' +
-      '(?:' +
-        '([^:/?#.]+)' +                 // scheme - ignore special characters
+      '^'
+      '(?:'
+        '([^:/?#.]+)'                   // scheme - ignore special characters
                                         // used by other URL parts such as :,
                                         // ?, /, #, and .
-      ':)?' +
-      '(?://' +
-        '(?:([^/?#]*)@)?' +             // userInfo
-        '([\\w\\d\\-\\u0100-\\uffff.%]*)' +
+      ':)?'
+      '(?://'
+        '(?:([^/?#]*)@)?'               // userInfo
+        '([\\w\\d\\-\\u0100-\\uffff.%]*)'
                                         // domain - restrict to letters,
                                         // digits, dashes, dots, percent
                                         // escapes, and unicode characters.
-        '(?::([0-9]+))?' +              // port
-      ')?' +
-      '([^?#]+)?' +                     // path
-      '(?:\\?([^#]*))?' +               // query
-      '(?:#(.*))?' +                    // fragment
+        '(?::([0-9]+))?'                // port
+      ')?'
+      '([^?#]+)?'                       // path
+      '(?:\\?([^#]*))?'                 // query
+      '(?:#(.*))?'                      // fragment
       '\$');
 
   static final _COMPONENT_SCHEME = 1;
   static final _COMPONENT_USER_INFO = 2;
   static final _COMPONENT_DOMAIN = 3;
   static final _COMPONENT_PORT = 4;
   static final _COMPONENT_PATH = 5;
   static final _COMPONENT_QUERY_DATA = 6;
   static final _COMPONENT_FRAGMENT = 7;
 
@@ skipping 111 matching lines @@
                              String first, String second) {
     if ("" != test) {
       sb.add(first === null ? "null" : first);
       sb.add(second === null ? "null" : second);
     }
   }
 }
 
 String merge(String base, String reference) {
   if (base == "") return "/$reference";
-  return base.substring(0, base.lastIndexOf("/") + 1) + "$reference";
+  return "${base.substring(0, base.lastIndexOf('/') + 1)}$reference";
 }
 
 String removeDotSegments(String path) {
   List<String> output = [];
   bool appendSlash = false;
   for (String segment in path.split("/")) {
     appendSlash = false;
     if (segment == "..") {
       if (!output.isEmpty() &&
           ((output.length != 1) || (output[0] != ""))) output.removeLast();
       appendSlash = true;
     } else if ("." == segment) {
       appendSlash = true;
     } else {
       output.add(segment);
     }
   }
   if (appendSlash) output.add("");
   return Strings.join(output, "/");
 }