--- a/testing/marionette/interaction.js
+++ b/testing/marionette/interaction.js
@@ -3,25 +3,26 @@
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 "use strict";
 
 const {utils: Cu} = Components;
 
 Cu.import("chrome://marionette/content/accessibility.js");
 Cu.import("chrome://marionette/content/atom.js");
+Cu.import("chrome://marionette/content/element.js");
 const {
   ElementClickInterceptedError,
   ElementNotInteractableError,
   InvalidArgumentError,
   InvalidElementStateError,
 } = Cu.import("chrome://marionette/content/error.js", {});
-Cu.import("chrome://marionette/content/element.js");
+Cu.import("chrome://marionette/content/event.js");
 const {pprint} = Cu.import("chrome://marionette/content/format.js", {});
-Cu.import("chrome://marionette/content/event.js");
+const {TimedPromise} = Cu.import("chrome://marionette/content/sync.js", {});
 
 Cu.importGlobalProperties(["File"]);
 
 this.EXPORTED_SYMBOLS = ["interaction"];
 
 /** XUL elements that support disabled attribute. */
 const DISABLED_ATTRIBUTE_SUPPORTED_XUL = new Set([
   "ARROWSCROLLBOX",
@@ -291,39 +292,44 @@ interaction.selectOption = function(el) 
  * DOM events generated by clicking an element, or until the document
  * is unloaded.
  *
  * @param {Element} el
  *     Element that is expected to receive the click.
  *
  * @return {Promise}
  *     Promise is resolved once <var>el</var> has been clicked
- *     (its <code>click</code> event fires) or the document is unloaded.
+ *     (its <code>click</code> event fires), the document is unloaded,
+ *     or a 500 ms timeout is reached.
  */
 interaction.flushEventLoop = async function(el) {
   const win = el.ownerGlobal;
   let unloadEv, clickEv;
 
-  return new Promise(resolve => {
+  let spinEventLoop = resolve => {
     unloadEv = resolve;
     clickEv = () => {
       if (win.closed) {
         resolve();
       } else {
         win.setTimeout(resolve, 0);
       }
     };
 
     win.addEventListener("unload", unloadEv, {mozSystemGroup: true});
     el.addEventListener("click", clickEv, {mozSystemGroup: true});
-  }).then(() => {
+  };
+  let removeListeners = () => {
     // only one event fires
     win.removeEventListener("unload", unloadEv);
     el.removeEventListener("click", clickEv);
-  });
+  };
+
+  return new TimedPromise(spinEventLoop, {timeout: 500, throws: null})
+      .then(removeListeners);
 };
 
 /**
  * Appends <var>path</var> to an <tt>&lt;input type=file&gt;</tt>'s
  * file list.
  *
  * @param {HTMLInputElement} el
  *     An <tt>&lt;input type=file&gt;</tt> element.

--- a/testing/web-platform/meta/MANIFEST.json
+++ b/testing/web-platform/meta/MANIFEST.json
@@ -373392,16 +373392,22 @@
     ]
    ],
    "webdriver/tests/cookies/get_named_cookie.py": [
     [
      "/webdriver/tests/cookies/get_named_cookie.py",
      {}
     ]
    ],
+   "webdriver/tests/element_click/bubbling.py": [
+    [
+     "/webdriver/tests/element_click/bubbling.py",
+     {}
+    ]
+   ],
    "webdriver/tests/element_click/select.py": [
     [
      "/webdriver/tests/element_click/select.py",
      {}
     ]
    ],
    "webdriver/tests/element_click/stale.py": [
     [
@@ -575969,16 +575975,20 @@
   "webdriver/tests/cookies/get_named_cookie.py": [
    "9455d1504590154ad2a540f102455baff602aefb",
    "wdspec"
   ],
   "webdriver/tests/element_click/__init__.py": [
    "da39a3ee5e6b4b0d3255bfef95601890afd80709",
    "support"
   ],
+  "webdriver/tests/element_click/bubbling.py": [
+   "e73935ac7ba09487a507f796bf0029da51cb2be1",
+   "wdspec"
+  ],
   "webdriver/tests/element_click/select.py": [
    "5ba51b660c7203bba3ada597c2f56fe094358e1f",
    "wdspec"
   ],
   "webdriver/tests/element_click/stale.py": [
    "37af63203540dfe11d36fe05d74694f05c6505f2",
    "wdspec"
   ],

new file mode 100644
--- /dev/null
+++ b/testing/web-platform/tests/webdriver/tests/element_click/bubbling.py
@@ -0,0 +1,78 @@
+from tests.support.asserts import assert_success
+from tests.support.inline import inline
+
+
+def click(session, element):
+    return session.transport.send(
+        "POST", "/session/{session_id}/element/{element_id}/click".format(
+            session_id=session.session_id,
+            element_id=element.id))
+
+
+def test_element_disappears_during_click(session):
+    """
+    When an element in the event bubbling order disappears (its CSS
+    display style is set to "none") during a click, Gecko and Blink
+    exhibit different behaviour.  Whilst Chrome fires a "click"
+    DOM event on <body>, Firefox does not.
+
+    A WebDriver implementation may choose to wait for this event to let
+    the event loops spin enough times to let click events propagate,
+    so this is a corner case test that Firefox does not hang indefinitely.
+    """
+    session.url = inline("""
+        <style>
+        #over,
+        #under {
+          position: absolute;
+          top: 8px;
+          left: 8px;
+          width: 100px;
+          height: 100px;
+        }
+
+        #over {
+          background: blue;
+          opacity: .5;
+        }
+        #under {
+          background: yellow;
+        }
+
+        #log {
+          margin-top: 120px;
+        }
+        </style>
+
+        <body id="body">
+          <div id=under></div>
+          <div id=over></div>
+
+           <div id=log></div>
+        </body>
+
+        <script>
+        let under = document.querySelector("#under");
+        let over = document.querySelector("#over");
+        let body = document.querySelector("body");
+        let log = document.querySelector("#log");
+
+        function logEvent({type, target, currentTarget}) {
+          log.innerHTML += "<p></p>";
+          log.lastElementChild.textContent = `${type} in ${target.id} (handled by ${currentTarget.id})`;
+        }
+
+        for (let ev of ["click", "mousedown", "mouseup"]) {
+          under.addEventListener(ev, logEvent);
+          over.addEventListener(ev, logEvent);
+          body.addEventListener(ev, logEvent);
+        }
+
+        over.addEventListener("mousedown", () => over.style.display = "none");
+        </script>
+        """)
+    over = session.find.css("#over", all=False)
+
+    # should not time out
+    response = click(session, over)
+    assert_success(response)