Adding HttpRequest method to make it easier to post form data.

sdk/lib/html/dartium/html_dartium.dart

Index: sdk/lib/html/dartium/html_dartium.dart
diff --git a/sdk/lib/html/dartium/html_dartium.dart b/sdk/lib/html/dartium/html_dartium.dart
index 3b3637e1510119d1792e321d327311790359ff96..ab63b3292c9e6b59ada09b292c949344f19ba97c 100644
--- a/sdk/lib/html/dartium/html_dartium.dart
+++ b/sdk/lib/html/dartium/html_dartium.dart
@@ -12631,6 +12631,40 @@ class HttpRequest extends EventTarget {
   }
 
   /**
+   * Makes a server POST request with the specified data encoded as form data.
+   *
+   * This is similar to sending a FormData object with broader browser
+   * support but limited to string values.
+   *
+   * See also:
+   *
+   * * [request]
+   */
+  static Future<HttpRequest> postFormData(String url, Map<String, String> data,
+      {bool withCredentials, String responseType,
+      Map<String, String> requestHeaders,
+      void onProgress(ProgressEvent e)}) {
+
+    var parts = [];
+    data.forEach((key, value) {
+      parts.add('${Uri.encodeQueryComponent(key)}='
+          '${Uri.encodeQueryComponent(value)}');
+    });
+    var formData = parts.join('&');
+
+    if (requestHeaders == null) {
+      requestHeaders = <String, String>{};
+    }
+    requestHeaders.putIfAbsent('Content-Type',
+        () => 'application/x-www-form-urlencoded; charset=UTF-8');
+
+    return request(url, method: 'POST', withCredentials: withCredentials,
+        responseType: responseType,
+        requestHeaders: requestHeaders, sendData: formData,
+        onProgress: onProgress);
+  }
+
+  /**
    * Creates a URL request for the specified [url].
    *
    * By default this will do an HTTP GET request, this can be overridden with
@@ -32034,11 +32068,11 @@ class _Utils {
 
   static String addTrailingDot(String str) => '${str}.';
 
+  static bool isNoSuchMethodError(obj) => obj is NoSuchMethodError;
+
   // TODO(jacobr): we need a failsafe way to determine that a Node is really a
   // DOM node rather than just a class that extends Node.
   static bool isNode(obj) => obj is Node;
-
-  static bool isNoSuchMethodError(obj) => obj is NoSuchMethodError;
 }
 
 class _NPObject extends NativeFieldWrapperClass1 {