Bug 1721349 - Move mSubmitter from HTMLFormSubmission to FormData and make it participate in cycle collection; r=mccr8

Differential Revision: https://phabricator.services.mozilla.com/D120334

dom/html/HTMLFormElement.h

@@ -32,7 +32,9 @@ namespace mozilla {
 class EventChainPostVisitor;
 class EventChainPreVisitor;
 namespace dom {
+class DialogFormSubmission;
 class HTMLFormControlsCollection;
+class HTMLFormSubmission;
 class HTMLImageElement;
 class FormData;