Add :user-valid test for programmatically setting value

When assigning into input.value from script, :user-valid and
:user-invalid should not start matching because it is not input from the
user:
https://drafts.csswg.org/selectors-4/#user-pseudos:~:text=but%20only%20after%20the%20user%20has%20significantly%20interacted%20with%20it

Change-Id: I2304c65c6e3a120af4c20829566ad3922940b983
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5018442
Commit-Queue: Joey Arhar <jarhar@chromium.org>
Reviewed-by: Mason Freed <masonf@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1225826}

css/selectors/user-invalid.html

@@ -48,6 +48,16 @@
   assert_false(input.matches(":user-valid"), "No change happened, still does not match :user-valid");
   assert_false(input.matches(":user-invalid"), "No change happened, still does not match :user-invalid");
 
+  input.value = "not an email";
+
+  assert_false(input.matches(":user-valid"), "Programatically set value, :user-valid should not match");
+  assert_false(input.matches(":user-invalid"), "Programatically set value, :user-invalid should not match");
+
+  input.value = "";
+
+  assert_false(input.matches(":user-valid"), "Programatically cleared value, :user-valid should not match");
+  assert_false(input.matches(":user-invalid"), "Programatically cleared value, :user-invalid should not match");
+
   await test_driver.click(input);
   await test_driver.send_keys(input, "not an email");
   input.blur();

css/selectors/user-valid.html

@@ -47,6 +47,16 @@
   assert_false(input.matches(":user-valid"), "No change happened, still does not match :user-valid");
   assert_false(input.matches(":user-invalid"), "No change happened, still does not match :user-invalid");
 
+  input.value = "test@example.com";
+
+  assert_false(input.matches(":user-valid"), "Programatically set value, :user-valid should not match");
+  assert_false(input.matches(":user-invalid"), "Programatically set value, :user-invalid should not match");
+
+  input.value = "";
+
+  assert_false(input.matches(":user-valid"), "Programatically cleared value, :user-valid should not match");
+  assert_false(input.matches(":user-invalid"), "Programatically cleared value, :user-invalid should not match");
+
   await test_driver.click(input);
   await test_driver.send_keys(input, "test@example.com");
   input.blur();