--- a/testing/marionette/event.js
+++ b/testing/marionette/event.js
@@ -1375,35 +1375,16 @@ event.sendEvent = function(eventType, el
   ev.metaKey = modifiers.meta;
   ev.altKey = modifiers.alt;
   ev.ctrlKey = modifiers.ctrl;
 
   ev.initEvent(eventType, opts.canBubble, true);
   el.dispatchEvent(ev);
 };
 
-event.focus = function(el, opts = {}) {
-  opts.canBubble = opts.canBubble || true;
-  let doc = el.ownerDocument || el.document;
-  let win = doc.defaultView;
-
-  let ev = new win.FocusEvent(el);
-  ev.initEvent("focus", opts.canBubble, true);
-  el.dispatchEvent(ev);
-};
-
-event.blur = function(el, {canBubble = true} = {}) {
-  let doc = el.ownerDocument || el.document;
-  let win = doc.defaultView;
-
-  let ev = new win.FocusEvent(el);
-  ev.initEvent("blur", canBubble, true);
-  el.dispatchEvent(ev);
-};
-
 event.mouseover = function(el, modifiers = {}, opts = {}) {
   return event.sendEvent("mouseover", el, modifiers, opts);
 };
 
 event.mousemove = function(el, modifiers = {}, opts = {}) {
   return event.sendEvent("mousemove", el, modifiers, opts);
 };
 

--- a/testing/marionette/interaction.js
+++ b/testing/marionette/interaction.js
@@ -265,17 +265,17 @@ interaction.selectOption = function(el) 
     throw new TypeError(pprint`Expected <option> element, got ${el}`);
   }
 
   let containerEl = element.getContainer(el);
 
   event.mouseover(containerEl);
   event.mousemove(containerEl);
   event.mousedown(containerEl);
-  event.focus(containerEl);
+  containerEl.focus();
 
   if (!el.disabled) {
     // Clicking <option> in <select> should not be deselected if selected.
     // However, clicking one in a <select multiple> should toggle
     // selectedness the way holding down Control works.
     if (containerEl.multiple) {
       el.selected = !el.selected;
     } else if (!el.selected) {
@@ -335,20 +335,20 @@ interaction.clearElement = function(el) 
     clearResettableElement(el);
   }
 };
 
 function clearContentEditableElement(el) {
   if (el.innerHTML === "") {
     return;
   }
-  event.focus(el);
+  el.focus();
   el.innerHTML = "";
   event.change(el);
-  event.blur(el);
+  el.blur();
 }
 
 function clearResettableElement(el) {
   if (!element.isMutableFormControl(el)) {
     throw new InvalidElementStateError(pprint`Not an editable form control: ${el}`);
   }
 
   let isEmpty;
@@ -361,20 +361,20 @@ function clearResettableElement(el) {
       isEmpty = el.value === "";
       break;
   }
 
   if (el.validity.valid && isEmpty) {
     return;
   }
 
-  event.focus(el);
+  el.focus();
   el.value = "";
   event.change(el);
-  event.blur(el);
+  el.blur();
 }
 
 /**
  * Waits until the event loop has spun enough times to process the
  * DOM events generated by clicking an element, or until the document
  * is unloaded.
  *
  * @param {Element} el
@@ -486,17 +486,17 @@ interaction.uploadFile = async function(
   fs.push(file);
 
   // <input type=file> opens OS widget dialogue
   // which means the mousedown/focus/mouseup/click events
   // occur before the change event
   event.mouseover(el);
   event.mousemove(el);
   event.mousedown(el);
-  event.focus(el);
+  el.focus();
   event.mouseup(el);
   event.click(el);
 
   el.mozSetFileArray(fs);
 
   event.change(el);
 };
 

--- a/testing/web-platform/tests/webdriver/tests/interaction/element_clear.py
+++ b/testing/web-platform/tests/webdriver/tests/interaction/element_clear.py
@@ -1,11 +1,15 @@
 import pytest
 
-from tests.support.asserts import assert_error, assert_success
+from tests.support.asserts import (
+    assert_element_has_focus,
+    assert_error,
+    assert_success,
+)
 from tests.support.inline import inline
 
 
 def add_event_listeners(element):
     element.session.execute_script("""
         let [target] = arguments;
         window.events = [];
         for (let expected of ["focus", "blur", "change"]) {
@@ -103,16 +107,17 @@ def test_input(session, type, value, def
 
     response = element_clear(session, element)
     assert_success(response)
     assert element.property("value") == default
     events = get_events(session)
     assert "focus" in events
     assert "change" in events
     assert "blur" in events
+    assert_element_has_focus(session.execute_script("return document.body"))
 
 
 @pytest.mark.parametrize("type",
                          ["number",
                           "range",
                           "email",
                           "password",
                           "search",
@@ -257,28 +262,30 @@ def test_contenteditable(session):
     element = session.find.css("p", all=False)
     add_event_listeners(element)
     assert element.property("innerHTML") == "foobar"
 
     response = element_clear(session, element)
     assert_success(response)
     assert element.property("innerHTML") == ""
     assert get_events(session) == ["focus", "change", "blur"]
+    assert_element_has_focus(session.execute_script("return document.body"))
 
 
 
 def test_designmode(session):
     session.url = inline("foobar")
     element = session.find.css("body", all=False)
     assert element.property("innerHTML") == "foobar"
     session.execute_script("document.designMode = 'on'")
 
     response = element_clear(session, element)
     assert_success(response)
     assert element.property("innerHTML") == "<br>"
+    assert_element_has_focus(session.execute_script("return document.body"))
 
 
 def test_resettable_element_focus_when_empty(session):
     session.url = inline("<input>")
     element = session.find.css("input", all=False)
     add_event_listeners(element)
     assert element.property("value") == ""
 

--- a/testing/web-platform/tests/webdriver/tests/support/asserts.py
+++ b/testing/web-platform/tests/webdriver/tests/support/asserts.py
@@ -132,8 +132,19 @@ def assert_same_element(session, a, b):
     try:
         a_markup = session.execute_script("return arguments[0].outerHTML;", args=(a,))
         b_markup = session.execute_script("return arguments[0].outerHTML;", args=(b,))
         message += " Actual: `%s`. Expected: `%s`." % (a_markup, b_markup)
     except WebDriverException:
         pass
 
     raise AssertionError(message)
+
+
+def assert_element_has_focus(target_element):
+    session = target_element.session
+
+    active_element = session.execute_script("return document.activeElement")
+    active_tag = active_element.property("localName")
+    target_tag = target_element.property("localName")
+
+    assert active_element == target_element, (
+        "Focussed element is <%s>, not <%s>" % (active_tag, target_tag))