Avoid repeated lower-casing of the same string when adding HTTP

sdk/lib/io/http_impl.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.
 
 class _HttpHeaders implements HttpHeaders {
   _HttpHeaders() : _headers = new Map<String, List<String>>();
 
   List<String> operator[](String name) {
     name = name.toLowerCase();
     return _headers[name];
@@ skipping 135 matching lines @@
       return new ContentType();
     }
   }
 
   void set contentType(ContentType contentType) {
     _checkMutable();
     _set("content-type", contentType.toString());
   }
 
   void _add(String name, Object value) {
+    var lowerCaseName = name.toLowerCase();
     // TODO(sgjesse): Add immutable state throw HttpException is immutable.
-    if (name.toLowerCase() == "date") {
+    if (lowerCaseName == "date") {
       if (value is Date) {
         date = value;
       } else if (value is String) {
         _set("date", value);
       } else {
         throw new HttpException("Unexpected type for header named $name");
       }
-    } else if (name.toLowerCase() == "expires") {
+    } else if (lowerCaseName == "expires") {
       if (value is Date) {
         expires = value;
       } else if (value is String) {
         _set("expires", value);
       } else {
         throw new HttpException("Unexpected type for header named $name");
       }
-    } else if (name.toLowerCase() == "if-modified-since") {
+    } else if (lowerCaseName == "if-modified-since") {
       if (value is Date) {
         ifModifiedSince = value;
       } else if (value is String) {
         _set("if-modified-since", value);
       } else {
         throw new HttpException("Unexpected type for header named $name");
       }
-    } else if (name.toLowerCase() == "host") {
+    } else if (lowerCaseName == "host") {
       int pos = value.indexOf(":");
       if (pos == -1) {
         _host = value;
         _port = HttpClient.DEFAULT_HTTP_PORT;
       } else {
         if (pos > 0) {
           _host = value.substring(0, pos);
         } else {
           _host = null;
         }
         if (pos + 1 == value.length) {
           _port = HttpClient.DEFAULT_HTTP_PORT;
         } else {
           try {
             _port = parseInt(value.substring(pos + 1));
           } on FormatException catch (e) {
             _port = null;
           }
         }
         _set("host", value);
       }
-    } else if (name.toLowerCase() == "content-type") {
+    } else if (lowerCaseName == "content-type") {
       _set("content-type", value);
     } else {
-      name = name.toLowerCase();
+      name = lowerCaseName;

[Søren Gjesse, 2012/11/15 12:24:11]

This line is not needed. Just use lowerCaseName two times below.

       List<String> values = _headers[name];
       if (values == null) {
         values = new List<String>();
         _headers[name] = values;
       }
       if (value is Date) {
         values.add(_HttpUtils.formatDate(value));
       } else {
         values.add(value.toString());
       }
@@ skipping 2471 matching lines @@
 
 
 class _RedirectInfo implements RedirectInfo {
   const _RedirectInfo(int this.statusCode,
                       String this.method,
                       Uri this.location);
   final int statusCode;
   final String method;
   final Uri location;
 }