Move MimeMultipartTransformer and HttpBodyHandler to mime and http_server packages.

sdk/lib/io/http_multipart_form_data.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 dart.io;
-
-
-/**
- * [:HttpMultipartFormData:] class used for 'upgrading' a [MimeMultipart] by
- * parsing it as a 'multipart/form-data' part. The following code shows how
- * it can be used.
- *
- *   HttpServer server = ...;
- *   server.listen((request) {
- *     String boundary = request.headers.contentType.parameters['boundary'];
- *     request
- *         .transform(new MimeMultipartTransformer(boundary))
- *         .map(HttpMultipartFormData.parse)
- *         .map((HttpMultipartFormData formData) {
- *           // form data object available here.
- *         });
- *
- * [:HttpMultipartFormData:] is a Stream, serving either bytes or decoded
- * Strings. Use [isText] or [isBinary] to see what type of data is provided.
- */
-abstract class HttpMultipartFormData implements Stream {
-  /**
-   * The parsed [:Content-Type:] header of the [:HttpMultipartFormData:].
-   * Returns [:null:] if not present.
-   */
-  ContentType get contentType;
-
-  /**
-   * The parsed [:Content-Disposition:] header of the [:HttpMultipartFormData:].
-   * This field is always present. Use this to extract e.g. name(form field
-   * name)and filename (client provided name of uploaded file) parameters.
-   */
-  HeaderValue get contentDisposition;
-
-  /**
-   * The parsed [:Content-Transfer-Encoding:] header of the
-   * [:HttpMultipartFormData:]. This field is used to determine how to decode
-   * the data. Returns [:null:] if not present.
-   */
-  HeaderValue get contentTransferEncoding;
-
-  /**
-   * Returns [:true:] if the data is decoded as [String].
-   */
-  bool get isText;
-
-  /**
-   * Returns [:true:] if the data is raw bytes.
-   */
-  bool get isBinary;
-
-  /**
-   * Returns the value for the header named [name]. If there
-   * is no header with the provided name, [:null:] will be returned.
-   *
-   * Use this method to index other headers available in the original
-   * [MimeMultipart].
-   */
-  String value(String name);
-
-  /**
-   * Parse a [MimeMultipart] and return a [HttpMultipartFormData]. If the
-   * [:Content-Disposition:] header is missing or invalid, a [HttpException] is
-   * thrown.
-   */
-  static HttpMultipartFormData parse(MimeMultipart multipart)
-      => _HttpMultipartFormData.parse(multipart);
-}