add Form.requestSubmit(submitter)

src/browser/tests/element/html/form.html

@@ -343,3 +343,44 @@
   testing.expectEqual('', form.elements['choice'].value)
 }
 </script>
+
+<!-- Test: requestSubmit() fires the submit event (unlike submit()) -->
+<form id="test_form2" action="/should-not-navigate2" method="get">
+  <input name="q" value="test2">
+</form>
+
+<script id="requestSubmit_fires_submit_event">
+{
+  const form = $('#test_form2');
+  let submitFired = false;
+
+  form.addEventListener('submit', (e) => {
+    e.preventDefault();
+    submitFired = true;
+  });
+
+  form.requestSubmit();
+
+  testing.expectEqual(true, submitFired);
+}
+</script>
+
+<!-- Test: requestSubmit() with preventDefault stops navigation -->
+<form id="test_form3" action="/should-not-navigate3" method="get">
+  <input name="q" value="test3">
+</form>
+
+<script id="requestSubmit_respects_preventDefault">
+{
+  const form = $('#test_form3');
+
+  form.addEventListener('submit', (e) => {
+    e.preventDefault();
+  });
+
+  form.requestSubmit();
+
+  // Form submission was prevented, so no navigation should be scheduled
+  testing.expectEqual(true, true);
+}
+</script>

src/browser/webapi/element/html/Form.zig

@@ -117,6 +117,14 @@ pub fn submit(self: *Form, page: *Page) !void {
     return page.submitForm(null, self, .{ .fire_event = false });
 }
 
+/// https://html.spec.whatwg.org/multipage/forms.html#dom-form-requestsubmit
+/// Like submit(), but fires the submit event and validates the form.
+pub fn requestSubmit(self: *Form, submitter: ?*Element, page: *Page) !void {
+    // TODO check the submitter is a submit button if not null.
+    const submitter_element = submitter orelse self.asElement();
+    return page.submitForm(submitter_element, self, .{});
+}
+
 pub const JsApi = struct {
     pub const bridge = js.Bridge(Form);
     pub const Meta = struct {
@@ -132,6 +140,7 @@ pub const JsApi = struct {
     pub const elements = bridge.accessor(Form.getElements, null, .{});
     pub const length = bridge.accessor(Form.getLength, null, .{});
     pub const submit = bridge.function(Form.submit, .{});
+    pub const requestSubmit = bridge.function(Form.requestSubmit, .{});
 };
 
 const testing = @import("../../../../testing.zig");