Adding supported checks and flags to FormData

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index 82f306dd2f9ab7e27a1eeec616dbfb3ac16676d7..198860c7b8eefde637b0990112d72235f22566ea 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -11545,6 +11545,10 @@ class Float64Array extends ArrayBufferView implements JavaScriptIndexingBehavior
 
 @DocsEditable
 @DomName('FormData')
+@SupportedBrowser(SupportedBrowser.CHROME)
+@SupportedBrowser(SupportedBrowser.FIREFOX)
+@SupportedBrowser(SupportedBrowser.IE, '10')
+@SupportedBrowser(SupportedBrowser.SAFARI)
 class FormData native "*FormData" {
 
   @DomName('DOMFormData.DOMFormData')
@@ -11558,6 +11562,9 @@ class FormData native "*FormData" {
   static FormData _create_1(form) => JS('FormData', 'new FormData(#)', form);
   static FormData _create_2() => JS('FormData', 'new FormData()');
 
+  /// Checks if this type is supported on the current platform.
+  static bool get supported => JS('bool', '!!(window.FormData)');
+
   @DomName('DOMFormData.append')
   @DocsEditable
   void append(String name, value, [String filename]) native;
@@ -12573,6 +12580,22 @@ class HttpRequest extends EventTarget native "*XMLHttpRequest" {
     return completer.future;
   }
 
+  /**
+   * Checks to see if the Progress event is supported on the current platform.
+   */
+  static bool get supportsProgressEvent {
+    var xhr = new HttpRequest();
+    return JS('bool', '"onprogress" in #', xhr);
+  }
+
+  /**
+   * Checks to see if the LoadEnd event is supported on the current platform.
+   */
+  static bool get supportsLoadEndEvent {
+    var xhr = new HttpRequest();
+    return JS('bool', '"onloadend" in #', xhr);
+  }
+
 
   @DomName('XMLHttpRequest.abortEvent')
   @DocsEditable
@@ -12678,6 +12701,10 @@ class HttpRequest extends EventTarget native "*XMLHttpRequest" {
    */
   @DomName('XMLHttpRequest.response')
   @DocsEditable
+  @SupportedBrowser(SupportedBrowser.CHROME)
+  @SupportedBrowser(SupportedBrowser.FIREFOX)
+  @SupportedBrowser(SupportedBrowser.IE, '10')
+  @SupportedBrowser(SupportedBrowser.SAFARI)
   @Creates('ArrayBuffer|Blob|Document|=Object|=List|String|num')
   final Object response;
 
@@ -12867,6 +12894,10 @@ class HttpRequest extends EventTarget native "*XMLHttpRequest" {
    */
   @DomName('XMLHttpRequest.onloadend')
   @DocsEditable
+  @SupportedBrowser(SupportedBrowser.CHROME)
+  @SupportedBrowser(SupportedBrowser.FIREFOX)
+  @SupportedBrowser(SupportedBrowser.IE, '10')
+  @SupportedBrowser(SupportedBrowser.SAFARI)
   Stream<ProgressEvent> get onLoadEnd => loadEndEvent.forTarget(this);
 
   /**
@@ -12886,6 +12917,10 @@ class HttpRequest extends EventTarget native "*XMLHttpRequest" {
    */
   @DomName('XMLHttpRequest.onprogress')
   @DocsEditable
+  @SupportedBrowser(SupportedBrowser.CHROME)
+  @SupportedBrowser(SupportedBrowser.FIREFOX)
+  @SupportedBrowser(SupportedBrowser.IE, '10')
+  @SupportedBrowser(SupportedBrowser.SAFARI)
   Stream<ProgressEvent> get onProgress => progressEvent.forTarget(this);
 
   /**