Bug 1502360 - [marionette] "Send Alert Text" has to use the text field's value property. r=ato

Depends on D20002

Differential Revision: https://phabricator.services.mozilla.com/D20004

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

testing/marionette/driver.js

@@ -3243,10 +3243,7 @@ GeckoDriver.prototype.sendKeysToDialog = async function(cmd) {
 
   // see toolkit/components/prompts/content/commonDialog.js
   let {loginTextbox} = this.dialog.ui;
-  loginTextbox.value = "";
-
-  await interaction.sendKeysToElement(
-      loginTextbox, text, this.a11yChecks);
+  loginTextbox.value = text;
 };
 
 GeckoDriver.prototype._checkIfAlertIsPresent = function() {

testing/web-platform/tests/webdriver/tests/send_alert_text/send.py

@@ -63,7 +63,7 @@ def test_alert_unsupported_operation(session):
     assert_error(response, "unsupported operation")
 
 
-@pytest.mark.parametrize("text", ["", "Federer", " Fed erer "])
+@pytest.mark.parametrize("text", ["", "Federer", " Fed erer ", "Fed\terer"])
 def test_send_alert_text(session, page, text):
     send_response = send_alert_text(session, text)
     assert_success(send_response)