Change fromString constructor to parse static method

sdk/lib/_internal/pub/lib/src/http.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.
 
 /// Helpers for dealing with HTTP.
 library pub.http;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:json' as json;
@@ skipping 79 matching lines @@
   /// Logs the fact that [request] was sent, and information about it.
   void _logRequest(http.BaseRequest request) {
     var requestLog = new StringBuffer();
     requestLog.writeln("HTTP ${request.method} ${request.url}");
     request.headers.forEach((name, value) =>
         requestLog.writeln(_logField(name, value)));
 
     if (request.method == 'POST') {
       var contentTypeString = request.headers[HttpHeaders.CONTENT_TYPE];
       if (contentTypeString == null) contentTypeString = '';
-      var contentType = new ContentType.fromString(contentTypeString);
+      var contentType = ContentType.parse(contentTypeString);
       if (request is http.MultipartRequest) {
         requestLog.writeln();
         requestLog.writeln("Body fields:");
         request.fields.forEach((name, value) =>
             requestLog.writeln(_logField(name, value)));
 
         // TODO(nweiz): make MultipartRequest.files readable, and log them?
       } else if (request is http.Request) {
         if (contentType.value == 'application/x-www-form-urlencoded') {
           requestLog.writeln();
@@ skipping 89 matching lines @@
 
 /// Exception thrown when an HTTP operation fails.
 class PubHttpException implements Exception {
   final http.Response response;
 
   const PubHttpException(this.response);
 
   String toString() => 'HTTP error ${response.statusCode}: '
       '${response.reasonPhrase}';
 }