Bug 1551758 - Form submission reentrancy protection for 'submit' and 'invalid' event; r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D53696

--HG--
extra : moz-landing-system : lando

dom/html/HTMLFormElement.cpp

@@ -119,7 +119,8 @@ HTMLFormElement::HTMLFormElement(
       mNotifiedObservers(false),
       mNotifiedObserversResult(false),
       mEverTriedInvalidSubmit(false),
-      mIsConstructingEntryList(false) {
+      mIsConstructingEntryList(false),
+      mIsFiringSubmissionEvents(false) {
   // We start out valid.
   AddStatesSilently(NS_EVENT_STATE_VALID);
 }
@@ -236,6 +237,15 @@ void HTMLFormElement::MaybeSubmit(Element* aSubmitter) {
     return;
   }
 
+  // 6.1. If form's firing submission events is true, then return.
+  if (mIsFiringSubmissionEvents) {
+    return;
+  }
+
+  // 6.2. Set form's firing submission events to true.
+  AutoRestore<bool> resetFiringSubmissionEventsFlag(mIsFiringSubmissionEvents);
+  mIsFiringSubmissionEvents = true;
+
   // 6.3. If the submitter element's no-validate state is false, then
   //      interactively validate the constraints of form and examine the result.
   //      If the result is negative (i.e., the constraint validation concluded

dom/html/HTMLFormElement.h

@@ -616,6 +616,8 @@ class HTMLFormElement final : public nsGenericHTMLElement,
   bool mEverTriedInvalidSubmit;
   /** Whether we are constructing entry list */
   bool mIsConstructingEntryList;
+  /** Whether we are firing submission event */
+  bool mIsFiringSubmissionEvents;
 
  private:
   NotNull<const Encoding*> GetSubmitEncoding();

testing/web-platform/meta/html/semantics/forms/form-submission-0/form-submission-algorithm.html.ini

@@ -1,7 +1,4 @@
 [form-submission-algorithm.html]
-  [If form's firing submission events is true, then return; 'invalid' event]
-    expected: FAIL
-
   [firing an event named submit; form.requestSubmit(submitter)]
     expected: FAIL
 

testing/web-platform/tests/html/semantics/forms/form-submission-0/form-submission-algorithm.html

@@ -18,6 +18,21 @@ test(() => {
   assert_equals(counter, 2);
 }, 'If constructing entry list flag of form is true, then return');
 
+test(() => {
+  let form = populateForm('<input><input type=submit>');
+  let submitter1 = form.querySelector('input[type=submit]');
+  let valid = form.elements[0];
+  let counter = 0;
+  valid.oninvalid = () => {
+    ++counter;
+  };
+  form.onsubmit = () => {
+    valid.required = true;
+    submitter1.dispatchEvent(new MouseEvent("click"));
+  };
+  submitter1.dispatchEvent(new MouseEvent("click"));
+  assert_equals(counter, 0);
+}, "If firing submission events flag of form is true, then return");
 
 test(() => {
   let form = populateForm('<input required><input type=submit><button type=submit></button>');