Reapply DOMFormData => FormData rename. (this time with a fix for Dartium)

lib/dom/idl/dart/dart.idl

 
 // This file introduces / supplements and forces Dart declarations.
 
 module default {
   FileList implements sequence<File>;
   HTMLCollection implements sequence<Node>;
   MediaList implements sequence<DOMString>;
   NamedNodeMap implements sequence<Node>;
   NodeList implements sequence<Node>;
   StyleSheetList implements sequence<StyleSheet>;
@@ skipping 266 matching lines @@
    // Provide missing constructor signature.
    Constructor(MutationCallback callback)]
   interface MutationObserver {
     // Rename 'observe' so we can define a new 'observe' API that calls the
     // original.
     [DartName=_observe] void observe(in Node target, in Dictionary options)
         raises(DOMException);
   };
 }
 
+module html {
+    [Supplemental,
+     CustomConstructor,
+     // Provide missing constructor signature.
+     Constructor([Optional] in FormElement form)]
+    interface FormData {
+    };
+}
+
 module storage {
   [Supplemental]
   interface SQLResultSetRowList {
     // Change the return type to Dictionary so that rows are exposed in the Dart
     // API as a Maps, with the appropriate conversion in JavaScript.
     [Suppressed] DOMObject item(in unsigned long index);
     [Custom] Dictionary item(in unsigned long index);
   };
 }