diff --git a/toolkit/components/passwordmgr/test/mochitest/test_LoginManagerContent_passwordEditedOrGenerated.html b/toolkit/components/passwordmgr/test/mochitest/test_LoginManagerContent_passwordEditedOrGenerated.html
--- a/toolkit/components/passwordmgr/test/mochitest/test_LoginManagerContent_passwordEditedOrGenerated.html
+++ b/toolkit/components/passwordmgr/test/mochitest/test_LoginManagerContent_passwordEditedOrGenerated.html
@@ -8,153 +8,169 @@
   <script type="text/javascript" src="../../../satchel/test/satchel_common.js"></script>
   <script src="pwmgr_common.js"></script>
   <link rel="stylesheet" href="/tests/SimpleTest/test.css"/>
 </head>
 <body>
-<p id="display"></p>
-<div id="content"></div>
+<script>
+const origin = window.location.origin;
+const readyPromise = registerRunTests(1)
+    .then(() => addLoginsInParent(
+      [origin, "https://autofill", null, "user1", "pass1"],
+      [origin, "https://autofill", null, "user2", "pass2"]
+    ));
+
+function preventDefaultAndStopProgagation(event) {
+  event.preventDefault();
+  event.stopImmediatePropagation();
+}
+</script>
+  <p id="display">
+    <form id="form1" action="https://autofill" onsubmit="return false;">
+      <input type="text" name="uname">
+      <input type="password" name="pword">
+      <button type="submit">Submit</button>
+    </form>
+  </p>
+<div id="content" style="display: none"></div>
 <pre id="test"></pre>
 <script>
 const { LoginManagerChild } = SpecialPowers.ChromeUtils.import(
   "resource://gre/modules/LoginManagerChild.jsm"
 );
 
-function preventDefaultAndStopProgagation(event) {
-  event.preventDefault();
-  event.stopImmediatePropagation();
-}
-
 add_setup(async () => {
   await SpecialPowers.pushPrefEnv({"set": [
     ["signon.generation.available", true],
     ["signon.generation.enabled", true],
   ]});
-  await setStoredLoginsAsync(
-    [location.origin, "https://autofill", null, "user1", "pass1"],
-    [location.origin, "https://autofill", null, "user2", "pass2"]
-  );
+  await readyPromise;
 });
 
-add_task(async function prevent_default_and_stop_propagation() {
-  const form = createLoginForm({
-    action: "https://autofill"
-  });
-  await promiseFormsProcessedInSameProcess();
-  form.pword.focus();
+add_task(async function test_preventDefaultAndStopPropagation() {
+  let pword = getFormElementByName(1, "pword");
+  pword.focus();
+
+  pword.addEventListener("focus", preventDefaultAndStopProgagation);
+  pword.addEventListener("focus", preventDefaultAndStopProgagation, true);
+  pword.addEventListener("blur", preventDefaultAndStopProgagation);
+  pword.addEventListener("blur", preventDefaultAndStopProgagation, true);
 
-  form.pword.addEventListener("focus", preventDefaultAndStopProgagation);
-  form.pword.addEventListener("focus", preventDefaultAndStopProgagation, true);
-  form.pword.addEventListener("blur", preventDefaultAndStopProgagation);
-  form.pword.addEventListener("blur", preventDefaultAndStopProgagation, true);
+  SpecialPowers.wrap(pword).setUserInput("generatedpass");
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, true, "Before first fill");
+  LoginManagerChild.forWindow(window)._passwordEditedOrGenerated(pword, { triggeredByFillingGenerated: true });
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, false, "After first fill");
+  synthesizeKey("KEY_Tab"); // blur
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, true, "After blur");
+  synthesizeKey("KEY_Tab", { shiftKey: true }); // focus again
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, false, "After shift-tab to focus again");
 
-  SpecialPowers.wrap(form.pword).setUserInput("generatedpass");
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, true, "Before first fill");
-  LoginManagerChild.forWindow(window)._passwordEditedOrGenerated(form.pword, { triggeredByFillingGenerated: true });
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, false, "After first fill");
-  synthesizeKey("KEY_Tab"); // blur
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, true, "After blur");
-  synthesizeKey("KEY_Tab", { shiftKey: true }); // focus again
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, false, "After shift-tab to focus again");
+  // Cleanup
+  recreateTree(document.getElementById("form1"));
+  await promiseFormsProcessedInSameProcess();
 });
 
-add_task(async function fields_masked_after_saved_login_fill() {
-  const form = createLoginForm({
-    action: "https://autofill"
-  });
-  await promiseFormsProcessedInSameProcess();
-  form.pword.focus();
+add_task(async function test_fieldsMaskedAfterSavedLoginFill() {
+  let pword = getFormElementByName(1, "pword");
+  pword.focus();
 
-  SpecialPowers.wrap(form.pword).setUserInput("generatedpass");
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, true, "Before first fill");
-  LoginManagerChild.forWindow(window)._passwordEditedOrGenerated(form.pword, { triggeredByFillingGenerated: true });
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, false, "After first fill");
+  SpecialPowers.wrap(pword).setUserInput("generatedpass");
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, true, "Before first fill");
+  LoginManagerChild.forWindow(window)._passwordEditedOrGenerated(pword, { triggeredByFillingGenerated: true });
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, false, "After first fill");
   synthesizeKey("KEY_Tab", { shiftKey: true }); // blur pw, focus un
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, true, "After blur");
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, true, "After blur");
 
   info("Filling username matching saved login");
   sendString("user1");
 
   let processedPromise = promiseFormsProcessedInSameProcess();
   synthesizeKey("KEY_Tab"); // focus again and trigger a fill of the matching password
   await processedPromise;
-  is(form.pword.value, "pass1", "Saved password was filled")
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, true, "After filling a saved login");
+  is(pword.value, "pass1", "Saved password was filled")
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, true, "After filling a saved login");
+
+  // Cleanup
+  recreateTree(document.getElementById("form1"));
+  await promiseFormsProcessedInSameProcess();
 });
 
-add_task(async function fields_masked_after_replacing_whole_value() {
-  const form = createLoginForm({
-    action: "https://autofill"
-  });
-  await promiseFormsProcessedInSameProcess();
-  form.pword.focus();
+add_task(async function test_fieldsMaskedAfterReplacingWholeValue() {
+  let pword = getFormElementByName(1, "pword");
+  pword.focus();
 
-  SpecialPowers.wrap(form.pword).setUserInput("generatedpass");
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, true, "Before first fill");
-  LoginManagerChild.forWindow(window)._passwordEditedOrGenerated(form.pword, { triggeredByFillingGenerated: true });
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, false, "After first fill");
+  SpecialPowers.wrap(pword).setUserInput("generatedpass");
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, true, "Before first fill");
+  LoginManagerChild.forWindow(window)._passwordEditedOrGenerated(pword, { triggeredByFillingGenerated: true });
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, false, "After first fill");
   synthesizeKey("KEY_Tab", { shiftKey: true }); // blur pw, focus un
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, true, "After blur");
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, true, "After blur");
 
   synthesizeKey("KEY_Tab"); // focus again and replace the whole password value
   info("Replacing password field value with arbitrary string");
   sendString("some_other_password");
-  is(form.pword.value, "some_other_password", "Whole password replaced")
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, true, "Replaced password value");
+  is(pword.value, "some_other_password", "Whole password replaced")
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, true, "Replaced password value");
 
   synthesizeKey("KEY_Tab"); // blur pw
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, true, "After blur");
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, true, "After blur");
   synthesizeKey("KEY_Tab", { shiftKey: true }); // focus pw again
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, true, "After focus again");
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, true, "After focus again");
+
+  // Cleanup
+  recreateTree(document.getElementById("form1"));
+  await promiseFormsProcessedInSameProcess();
 });
 
-add_task(async function fields_unmasked_after_adding_character() {
-  const form = createLoginForm({
-    action: "https://autofill"
-  });
-  await promiseFormsProcessedInSameProcess();
-  form.pword.focus();
+add_task(async function test_fieldsUnmaskedAfterAddingCharacter() {
+  let pword = getFormElementByName(1, "pword");
+  pword.focus();
 
-  SpecialPowers.wrap(form.pword).setUserInput("generatedpass");
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, true, "Before first fill");
-  LoginManagerChild.forWindow(window)._passwordEditedOrGenerated(form.pword, { triggeredByFillingGenerated: true });
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, false, "After first fill");
+  SpecialPowers.wrap(pword).setUserInput("generatedpass");
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, true, "Before first fill");
+  LoginManagerChild.forWindow(window)._passwordEditedOrGenerated(pword, { triggeredByFillingGenerated: true });
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, false, "After first fill");
   synthesizeKey("KEY_Tab", { shiftKey: true }); // blur pw, focus un
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, true, "After blur");
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, true, "After blur");
 
   synthesizeKey("KEY_Tab"); // focus again
   synthesizeKey("KEY_ArrowRight"); // Remove the selection
   info("Adding a character to the end of the password");
   sendString("@");
-  is(form.pword.value, "generatedpass@", "Character was added to the value")
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, false, "Added @");
+  is(pword.value, "generatedpass@", "Character was added to the value")
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, false, "Added @");
 
   synthesizeKey("KEY_Tab"); // blur pw
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, true, "After blur after @");
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, true, "After blur after @");
   synthesizeKey("KEY_Tab", { shiftKey: true }); // focus pw again
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, false, "After focus after @");
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, false, "After focus after @");
+
+  // Cleanup
+  recreateTree(document.getElementById("form1"));
+  await promiseFormsProcessedInSameProcess();
 });
 
-add_task(async function type_not_password() {
-  const form = createLoginForm({
-    action: "https://autofill"
-  });
-  await promiseFormsProcessedInSameProcess();
-  form.pword.focus();
+add_task(async function test_typeNotPassword() {
+  let pword = getFormElementByName(1, "pword");
+  pword.focus();
 
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, true, "Before first fill");
-  SpecialPowers.wrap(form.pword).setUserInput("generatedpass");
-  LoginManagerChild.forWindow(window)._passwordEditedOrGenerated(form.pword, { triggeredByFillingGenerated: true });
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, false, "After first fill");
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, true, "Before first fill");
+  SpecialPowers.wrap(pword).setUserInput("generatedpass");
+  LoginManagerChild.forWindow(window)._passwordEditedOrGenerated(pword, { triggeredByFillingGenerated: true });
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, false, "After first fill");
 
   // Simulate a website doing their own unmasking and re-masking
-  form.pword.type = "text";
+  pword.type = "text";
   await new Promise(resolve => SimpleTest.executeSoon(resolve));
-  form.pword.type = "password";
+  pword.type = "password";
 
   synthesizeKey("KEY_Tab"); // blur
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, true, "After blur");
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, true, "After blur");
   synthesizeKey("KEY_Tab", { shiftKey: true }); // focus again
-  LOGIN_FIELD_UTILS.checkPasswordMasked(form.pword, false, "After shift-tab to focus again");
+  LOGIN_FIELD_UTILS.checkPasswordMasked(pword, false, "After shift-tab to focus again");
+
+  // Cleanup
+  recreateTree(document.getElementById("form1"));
+  await promiseFormsProcessedInSameProcess();
 });
 </script>
 </body>
 </html>