FormData is FormData in all browsers.

lib/compiler/implementation/lib/native_helper.dart

Index: lib/compiler/implementation/lib/native_helper.dart
diff --git a/lib/compiler/implementation/lib/native_helper.dart b/lib/compiler/implementation/lib/native_helper.dart
index c9403bdd111184f96261cc17062d17f633588252..909672e8037ed746915a0a5b8bb173436138d107 100644
--- a/lib/compiler/implementation/lib/native_helper.dart
+++ b/lib/compiler/implementation/lib/native_helper.dart
@@ -7,7 +7,6 @@ String typeNameInChrome(obj) {
   if (name == 'Window') return 'DOMWindow';
   if (name == 'CanvasPixelArray') return 'Uint8ClampedArray';
   if (name == 'WebKitMutationObserver') return 'MutationObserver';
-  if (name == 'FormData') return 'DOMFormData';
   return name;
 }
 
@@ -17,14 +16,12 @@ String typeNameInSafari(obj) {
   if (name == 'Window') return 'DOMWindow';
   if (name == 'CanvasPixelArray') return 'Uint8ClampedArray';
   if (name == 'WebKitMutationObserver') return 'MutationObserver';
-  if (name == 'FormData') return 'DOMFormData';

[vsm, 2012/10/05 17:03:17]

Are you sure the name is now 'FormData' on all versions of Safari/WebKit we need
to support?   We might need a map the other way:

if (name == 'DOMFormData') return 'FormData';

[podivilov1, 2012/10/05 17:23:07]

I don't think 'DOMFormData' class ever existed in any browser. DOMFormData.idl
was added to WebKit in 2010, and was exposed as 'FormData' from the very
beginning, see https://bugs.webkit.org/show_bug.cgi?id=36024.

   return name;
 }
 
 String typeNameInOpera(obj) {
   String name = JS('String', '#', constructorNameFallback(obj));
   if (name == 'Window') return 'DOMWindow';
-  if (name == 'FormData') return 'DOMFormData';
   return name;
 }
 
@@ -36,7 +33,6 @@ String typeNameInFirefox(obj) {
   if (name == 'WorkerMessageEvent') return 'MessageEvent';
   if (name == 'DragEvent') return 'MouseEvent';
   if (name == 'DataTransfer') return 'Clipboard';
-  if (name == 'FormData') return 'DOMFormData';
   if (name == 'MouseScrollEvent') return 'WheelEvent';
   if (name == 'OfflineResourceList') return 'DOMApplicationCache';
   return name;
@@ -62,7 +58,6 @@ String typeNameInIE(obj) {
   if (name == 'HTMLPhraseElement') return 'HTMLElement';
   if (name == 'MSStyleCSSProperties') return 'CSSStyleDeclaration';
   if (name == 'MouseWheelEvent') return 'WheelEvent';
-  if (name == 'FormData') return 'DOMFormData';
   return name;
 }