diff --git a/testing/web-platform/meta/MANIFEST.json b/testing/web-platform/meta/MANIFEST.json
index cd03caf41546..2024d71bdf21 100644
--- a/testing/web-platform/meta/MANIFEST.json
+++ b/testing/web-platform/meta/MANIFEST.json
@@ -287318,6 +287318,11 @@
      {}
     ]
    ],
+   "html/webappapis/scripting/events/resources/event-handler-body.js": [
+    [
+     {}
+    ]
+   ],
    "html/webappapis/scripting/events/resources/open-window.html": [
     [
      {}
@@ -361544,12 +361549,6 @@
      {}
     ]
    ],
-   "html/webappapis/scripting/events/body-exposed-window-event-handlers.html": [
-    [
-     "/html/webappapis/scripting/events/body-exposed-window-event-handlers.html",
-     {}
-    ]
-   ],
    "html/webappapis/scripting/events/body-onload.html": [
     [
      "/html/webappapis/scripting/events/body-onload.html",
@@ -361580,6 +361579,12 @@
      {}
     ]
    ],
+   "html/webappapis/scripting/events/event-handler-attributes-windowless-body.html": [
+    [
+     "/html/webappapis/scripting/events/event-handler-attributes-windowless-body.html",
+     {}
+    ]
+   ],
    "html/webappapis/scripting/events/event-handler-javascript.html": [
     [
      "/html/webappapis/scripting/events/event-handler-javascript.html",
@@ -361670,9 +361675,15 @@
      {}
     ]
    ],
-   "html/webappapis/scripting/events/event-handler-spec-example.html": [
+   "html/webappapis/scripting/events/event-handler-removal.window.js": [
     [
-     "/html/webappapis/scripting/events/event-handler-spec-example.html",
+     "/html/webappapis/scripting/events/event-handler-removal.window.html",
+     {}
+    ]
+   ],
+   "html/webappapis/scripting/events/event-handler-spec-example.window.js": [
+    [
+     "/html/webappapis/scripting/events/event-handler-spec-example.window.html",
      {}
     ]
    ],
@@ -361688,15 +361699,21 @@
      {}
     ]
    ],
-   "html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-late.html": [
+   "html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-late.window.js": [
     [
-     "/html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-late.html",
+     "/html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-late.window.html",
      {}
     ]
    ],
-   "html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-once.html": [
+   "html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-once.window.js": [
     [
-     "/html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-once.html",
+     "/html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-once.window.html",
+     {}
+    ]
+   ],
+   "html/webappapis/scripting/events/invalid-uncompiled-raw-handler-keeps-position.window.js": [
+    [
+     "/html/webappapis/scripting/events/invalid-uncompiled-raw-handler-keeps-position.window.html",
      {}
     ]
    ],
@@ -600647,10 +600664,6 @@
    "c14a043b6ab10ab5e9e08d5bae1088f8dbf5e9c3",
    "testharness"
   ],
-  "html/webappapis/scripting/events/body-exposed-window-event-handlers.html": [
-   "e4f00b866dba9849c8aabb4b1e2ef9b8d1d58e5d",
-   "testharness"
-  ],
   "html/webappapis/scripting/events/body-onload.html": [
    "1e43d1ccd476a530738cfdc7846adad807ca1edc",
    "testharness"
@@ -600672,11 +600685,15 @@
    "testharness"
   ],
   "html/webappapis/scripting/events/event-handler-attributes-body-window.html": [
-   "1c87892cba7fa30533c2c28f8c0244dd90ff8548",
+   "4a6bee61bef240cd0947d796f7b3c2c4166b2670",
    "testharness"
   ],
   "html/webappapis/scripting/events/event-handler-attributes-window-body.html": [
-   "29c4c133b9ef3847146182a5fb24a4e0fd96bbfe",
+   "1ceed5278de7d17c4ef655a2a79e3ecc97339dbf",
+   "testharness"
+  ],
+  "html/webappapis/scripting/events/event-handler-attributes-windowless-body.html": [
+   "9b81d42ff729399d57e182abc8b8950cef503e12",
    "testharness"
   ],
   "html/webappapis/scripting/events/event-handler-javascript.html": [
@@ -600751,8 +600768,12 @@
    "f5423d7ed448fbceb4d43ef7352b708b48ce2364",
    "testharness"
   ],
-  "html/webappapis/scripting/events/event-handler-spec-example.html": [
-   "1f3cff426523ea5799d12b90e45f2f50eb6f8181",
+  "html/webappapis/scripting/events/event-handler-removal.window.js": [
+   "d0f75c511dd3d04e1e9334753bb0d030f0eb805e",
+   "testharness"
+  ],
+  "html/webappapis/scripting/events/event-handler-spec-example.window.js": [
+   "7bfbe58bce55aad177adb18f408852d7aed08a96",
    "testharness"
   ],
   "html/webappapis/scripting/events/eventhandler-cancellation.html": [
@@ -600763,12 +600784,16 @@
    "aae0f1abf8bf3ced9e69e83996f76ef700c11866",
    "testharness"
   ],
-  "html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-late.html": [
-   "83ee25032c5877ed830e0070d3fff963746e290e",
+  "html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-late.window.js": [
+   "2892a4c3ab98740dc2fa8240b91217ff6dd49e17",
    "testharness"
   ],
-  "html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-once.html": [
-   "a67f66ead4ffce7b6692f01dbe6449e28f062f08",
+  "html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-once.window.js": [
+   "b39b54b0e9cea49e4628b72ddd84e236cb57e77a",
+   "testharness"
+  ],
+  "html/webappapis/scripting/events/invalid-uncompiled-raw-handler-keeps-position.window.js": [
+   "f9443bf99a0a9dfd937d8d1cf3bd618a3734aa1c",
    "testharness"
   ],
   "html/webappapis/scripting/events/messageevent-constructor.https.html": [
@@ -600787,6 +600812,10 @@
    "d40c0b9cce8a7b9a369a30679560b0d1ab22aca0",
    "support"
   ],
+  "html/webappapis/scripting/events/resources/event-handler-body.js": [
+   "656903cf99e6e36b491bec30d902466a83b9504f",
+   "support"
+  ],
   "html/webappapis/scripting/events/resources/open-window.html": [
    "1d23263570e6db17d36e6bf611f4f31d231327b6",
    "support"
diff --git a/testing/web-platform/tests/html/webappapis/scripting/events/body-exposed-window-event-handlers.html b/testing/web-platform/tests/html/webappapis/scripting/events/body-exposed-window-event-handlers.html
deleted file mode 100644
index e4f00b866dba..000000000000
--- a/testing/web-platform/tests/html/webappapis/scripting/events/body-exposed-window-event-handlers.html
+++ /dev/null
@@ -1,48 +0,0 @@
-<!doctype html>
-<meta charset="utf-8">
-<title></title>
-<body></body>
-<script src="/resources/testharness.js"></script>
-<script src="/resources/testharnessreport.js"></script>
-<script>
-var elements = ['body', 'frameset'];
-var handlers = [
-    'load', 'resize', 'blur', 'focus', 'scroll',
-    'afterprint', 'beforeprint', 'beforeunload', 'hashchange',
-    'languagechange', 'message', 'offline', 'online', 'pagehide',
-    'pageshow', 'popstate', 'rejectionhandled', 'storage',
-    'unhandledrejection', 'unload'];
-
-elements.forEach(function (elementName) {
-  handlers.forEach(function (eventName) {
-    var handlerName = "on" + eventName;
-
-    test(function() {
-      var windowHandler = function () { return "Handler attached to the window"; };
-      window[handlerName] = windowHandler;
-
-      var d = (new DOMParser).parseFromString('', 'text/html');
-      var b = d.createElement(elementName);
-
-      assert_equals(b[handlerName], null);
-
-      window[handlerName] = null;
-    }, "Return null when getting the " + eventName + " event handler of a windowless " + elementName);
-
-    test(function() {
-      var windowHandler = function () { return "Handler attached to the window"; };
-      window[handlerName] = windowHandler;
-
-      var d = (new DOMParser).parseFromString('', 'text/html');
-      var b = d.createElement(elementName);
-      b[handlerName] = function() { return "Handler attached to windowless element"; };
-
-      assert_equals(window[handlerName], windowHandler);
-      assert_equals(b[handlerName], null);
-
-      // Clean up window event handler
-      window[handlerName] = null;
-    }, "Ignore setting of " + eventName + " window event handlers on windowless " + elementName);
-  });
-});
-</script>
diff --git a/testing/web-platform/tests/html/webappapis/scripting/events/event-handler-attributes-body-window.html b/testing/web-platform/tests/html/webappapis/scripting/events/event-handler-attributes-body-window.html
index 1c87892cba7f..4a6bee61bef2 100644
--- a/testing/web-platform/tests/html/webappapis/scripting/events/event-handler-attributes-body-window.html
+++ b/testing/web-platform/tests/html/webappapis/scripting/events/event-handler-attributes-body-window.html
@@ -3,32 +3,49 @@
 
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
+<script src="/resources/WebIDLParser.js"></script>
+<script src="resources/event-handler-body.js"></script>
 <div id="log"></div>
 <body>
 <script>
-function f() {
-  return 0;
-}
+setup({ explicit_done: true });
 
-var handlers = ['blur','error','focus','load','resize','scroll',
-                'afterprint','beforeprint','beforeunload','hashchange',
-                'languagechange','message','offline','online','pagehide',
-                'pageshow','popstate','storage','unload'];
-handlers.forEach(function(handler) {
-  test(function() {
-    document.body['on' + handler] = f;
-    assert_equals(window['on' + handler], f);
-  }, handler);
-});
+handlersListPromise.then(({ shadowedHandlers, notShadowedHandlers }) => {
+  const createdBody = document.createElement("body");
+  for (const [description, body, altBody] of [
+    ["document.body", document.body, createdBody],
+    ['document.createElement("body")', createdBody, document.body]
+  ]) {
+    const f = () => 0;
 
-handlers.forEach(function(handler) {
-    document.body['on' + handler] = null;
-});
+    shadowedHandlers.forEach(function(handler) {
+      test(function() {
+        body['on' + handler] = f;
+        assert_equals(window['on' + handler], f, "window should reflect");
+        assert_equals(altBody['on' + handler], f, "alternative body should reflect");
+      }, `shadowed ${handler} (${description})`);
+    });
+    notShadowedHandlers.forEach(function(handler) {
+      test(function() {
+        body['on' + handler] = f;
+        assert_equals(window['on' + handler], null, "window should reflect");
+        assert_equals(altBody['on' + handler], null, "alternative body should reflect");
+      }, `not shadowed ${handler} (${description})`);
+    });
 
-handlers.forEach(function(handler) {
-  test(function() {
-    assert_equals(document.body['on' + handler], null);
-    assert_equals(window['on' + handler], null);
-  }, handler + " removal");
+    [...shadowedHandlers, ...notShadowedHandlers].forEach(function(handler) {
+      body['on' + handler] = null;
+    });
+
+    shadowedHandlers.forEach(function(handler) {
+      test(function() {
+        assert_equals(body['on' + handler], null, "body should reflect changes to itself");
+        assert_equals(window['on' + handler], null, "window should reflect");
+        assert_equals(altBody['on' + handler], null, "alternative body should reflect");
+      }, `shadowed ${handler} removal (${description})`);
+    });
+  }
+
+  done();
 });
 </script>
diff --git a/testing/web-platform/tests/html/webappapis/scripting/events/event-handler-attributes-window-body.html b/testing/web-platform/tests/html/webappapis/scripting/events/event-handler-attributes-window-body.html
index 29c4c133b9ef..1ceed5278de7 100644
--- a/testing/web-platform/tests/html/webappapis/scripting/events/event-handler-attributes-window-body.html
+++ b/testing/web-platform/tests/html/webappapis/scripting/events/event-handler-attributes-window-body.html
@@ -3,32 +3,47 @@
 
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
+<script src="/resources/WebIDLParser.js"></script>
+<script src="resources/event-handler-body.js"></script>
 <div id="log"></div>
 <body>
 <script>
+setup({ explicit_done: true });
+
 function f() {
   return 0;
 }
 
-var handlers = ['blur','error','focus','load','resize','scroll',
-                'afterprint','beforeprint','beforeunload','hashchange',
-                'languagechange','message','offline','online','pagehide',
-                'pageshow','popstate','storage','unload'];
-handlers.forEach(function(handler) {
-  test(function() {
-    window['on' + handler] = f;
-    assert_equals(document.body['on' + handler], f);
-  }, handler);
-});
+handlersListPromise.then(({ shadowedHandlers, notShadowedHandlers }) => {
+  const body = document.createElement("body");
 
-handlers.forEach(function(handler) {
+  shadowedHandlers.forEach(function(handler) {
+    test(function() {
+      window['on' + handler] = f;
+      assert_equals(document.body['on' + handler], f, "document.body should reflect");
+      assert_equals(body['on' + handler], f, "document.createElement('body') should reflect");
+    }, `shadowed ${handler}`);
+  });
+  notShadowedHandlers.forEach(function(handler) {
+    test(function() {
+      window['on' + handler] = f;
+      assert_equals(document.body['on' + handler], null, "document.body should reflect");
+      assert_equals(body['on' + handler], null, "document.createElement('body') should reflect");
+    }, `not shadowed ${handler}`);
+  });
+
+  [...shadowedHandlers, ...notShadowedHandlers].forEach(function(handler) {
     window['on' + handler] = null;
-});
+  });
 
-handlers.forEach(function(handler) {
-  test(function() {
-    assert_equals(window['on' + handler], null);
-    assert_equals(document.body['on' + handler], null);
-  }, handler + " removal");
+  shadowedHandlers.forEach(function(handler) {
+    test(function() {
+      assert_equals(window['on' + handler], null, "window should reflect changes to itself");
+      assert_equals(document.body['on' + handler], null, "document.body should reflect");
+      assert_equals(body['on' + handler], null, "document.createElement('body') should reflect");
+    }, `shadowed ${handler} removal`);
+  });
+
+  done();
 });
 </script>
diff --git a/testing/web-platform/tests/html/webappapis/scripting/events/event-handler-attributes-windowless-body.html b/testing/web-platform/tests/html/webappapis/scripting/events/event-handler-attributes-windowless-body.html
new file mode 100644
index 000000000000..9b81d42ff729
--- /dev/null
+++ b/testing/web-platform/tests/html/webappapis/scripting/events/event-handler-attributes-windowless-body.html
@@ -0,0 +1,71 @@
+<!doctype html>
+<meta charset="utf-8">
+<title></title>
+<body></body>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/WebIDLParser.js"></script>
+<script src="resources/event-handler-body.js"></script>
+<script>
+setup({ explicit_done: true });
+const elements = ['body', 'frameset'];
+handlersListPromise.then(({ shadowedHandlers, notShadowedHandlers }) => {
+  elements.forEach(function (elementName) {
+    shadowedHandlers.forEach(function (eventName) {
+      var handlerName = "on" + eventName;
+
+      test(function() {
+        var windowHandler = function () { return "Handler attached to the window"; };
+        window[handlerName] = windowHandler;
+
+        var d = (new DOMParser).parseFromString('', 'text/html');
+        var b = d.createElement(elementName);
+
+        assert_equals(b[handlerName], null);
+
+        window[handlerName] = null;
+      }, "Return null when getting the " + eventName + " event handler of a windowless " + elementName);
+
+      test(function() {
+        var windowHandler = function () { return "Handler attached to the window"; };
+        window[handlerName] = windowHandler;
+
+        var d = (new DOMParser).parseFromString('', 'text/html');
+        var b = d.createElement(elementName);
+        b[handlerName] = function() { return "Handler attached to windowless element"; };
+
+        assert_equals(window[handlerName], windowHandler);
+        assert_equals(b[handlerName], null);
+
+        // Clean up window event handler
+        window[handlerName] = null;
+      }, "Ignore setting of " + eventName + " window event handlers on windowless " + elementName);
+    });
+
+    notShadowedHandlers.forEach(function (eventName) {
+      var handlerName = "on" + eventName;
+
+      test(function() {
+        var windowHandler = function () { return "Handler attached to the window"; };
+        window[handlerName] = windowHandler;
+
+        var d = (new DOMParser).parseFromString('', 'text/html');
+        var b = d.createElement(elementName);
+
+        assert_equals(b[handlerName], null);
+
+        var elementHandler = function () { return "Handler attached to the element"; };
+        b[handlerName] = elementHandler;
+
+        assert_equals(window[handlerName], windowHandler);
+        assert_equals(b[handlerName], elementHandler);
+
+        // Clean up window event handler
+        window[handlerName] = null;
+      }, eventName + " is unaffected on a windowless " + elementName);
+    });
+  });
+
+  done();
+});
+</script>
diff --git a/testing/web-platform/tests/html/webappapis/scripting/events/event-handler-removal.window.js b/testing/web-platform/tests/html/webappapis/scripting/events/event-handler-removal.window.js
new file mode 100644
index 000000000000..d0f75c511dd3
--- /dev/null
+++ b/testing/web-platform/tests/html/webappapis/scripting/events/event-handler-removal.window.js
@@ -0,0 +1,70 @@
+test(() => {
+  var i = 0;
+  var uncalled = "assert_unreached('First event handler.');"
+  var button = document.createElement('button');
+  button.addEventListener('click', () => { assert_equals(++i, 1); }, false);
+  button.setAttribute('onclick', uncalled);                             // event handler is activated here
+  button.addEventListener('click', () => { assert_equals(++i, 2); }, false);
+  button.onclick = null;                                                // but de-activated here
+  button.addEventListener('click', () => { assert_equals(++i, 3); }, false);
+  button.onclick = () => { assert_equals(++i, 4); };                    // and re-activated here
+  button.addEventListener('click', () => { assert_equals(++i, 5); }, false);
+  button.click()
+  assert_equals(button.getAttribute("onclick"), uncalled)
+  assert_equals(i, 5);
+}, "Event handler set through content attribute should be removed when they are set to null.");
+
+let happened = 0;
+test(() => {
+  var script = "happened++;";
+  var button = document.createElement('button');
+  button.setAttribute('onclick', script);                               // event handler is activated here
+  button.onclick = null;                                                // but de-activated here
+  assert_equals(button.getAttribute("onclick"), script)
+  button.setAttribute('onclick', script);                               // and re-activated here
+  button.click()
+  assert_equals(happened, 1);
+}, "Event handler set through content attribute should be re-activated even if content is the same.");
+
+test(() => {
+  var i = 0;
+  var uncalled = "assert_unreached('First event handler.');"
+  var button = document.createElement('button');
+  button.addEventListener('click', () => { assert_equals(++i, 1); }, false);
+  button.setAttribute('onclick', uncalled);                             // event handler is activated here
+  button.addEventListener('click', () => { assert_equals(++i, 2); }, false);
+  button.removeAttribute('onclick');                                    // but de-activated here
+  button.addEventListener('click', () => { assert_equals(++i, 3); }, false);
+  button.onclick = () => { assert_equals(++i, 4); };                    // and re-activated here
+  button.addEventListener('click', () => { assert_equals(++i, 5); }, false);
+  button.click()
+  assert_equals(i, 5);
+}, "Event handler set through content attribute should be deactivated when the content attribute is removed.");
+test(t => {
+  var i = 0;
+  var uncalled = "assert_unreached('First event handler.');"
+  var button = document.createElement('button');
+  button.addEventListener('click', () => { assert_equals(++i, 1); }, false);
+  button.onclick = t.unreached_func('First event handler.');            // event handler is activated here
+  button.addEventListener('click', () => { assert_equals(++i, 2); }, false);
+  button.onclick = null;                                                // but de-activated here
+  button.addEventListener('click', () => { assert_equals(++i, 3); }, false);
+  button.onclick = () => { assert_equals(++i, 4); };                    // and re-activated here
+  button.addEventListener('click', () => { assert_equals(++i, 5); }, false);
+  button.click()
+  assert_equals(i, 5);
+}, "Event handler set through IDL should be deactivated when the IDL attribute is set to null.");
+test(t => {
+  var i = 0;
+  var uncalled = "assert_unreached('First event handler.');"
+  var button = document.createElement('button');
+  button.addEventListener('click', () => { assert_equals(++i, 1) }, false);
+  button.onclick = t.unreached_func('First event handler.');            // event handler is activated here
+  button.addEventListener('click', () => { assert_equals(++i, 3) }, false);
+  button.removeAttribute('onclick');                                    // but de-activated here
+  button.addEventListener('click', () => { assert_equals(++i, 4) }, false);
+  button.onclick = () => { assert_equals(++i, 2); };                    // and re-activated here
+  button.addEventListener('click', () => { assert_equals(++i, 5) }, false);
+  button.click()
+  assert_equals(i, 5);
+}, "Event handler set through IDL should NOT be deactivated when the content attribute is removed.");
diff --git a/testing/web-platform/tests/html/webappapis/scripting/events/event-handler-spec-example.html b/testing/web-platform/tests/html/webappapis/scripting/events/event-handler-spec-example.html
deleted file mode 100644
index 1f3cff426523..000000000000
--- a/testing/web-platform/tests/html/webappapis/scripting/events/event-handler-spec-example.html
+++ /dev/null
@@ -1,67 +0,0 @@
-<!DOCTYPE html>
-<title>Event handler invocation order</title>
-<script src="/resources/testharness.js"></script>
-<script src="/resources/testharnessreport.js"></script>
-<div id="log"></div>
-<script>
-var objects = [{}, function() {}, new Number(42), new String()];
-var primitives = [42, null, undefined, ""];
-objects.forEach(function(object) {
-  var t = async_test("Event handler listeners should be registered when they " +
-                     "are first set to an object value (" +
-                     format_value(object) + ").");
-  t.step(function() {
-    var i = 0;
-    var uncalled = "t.step(function() { assert_unreached('First event handler.') })"
-    var button = document.createElement('button');
-    button.onclick = object; // event handler listener is registered here
-    assert_equals(button.onclick, object);
-    button.addEventListener('click', t.step_func(function () { assert_equals(++i, 2) }), false);
-    button.setAttribute('onclick', uncalled);
-    button.addEventListener('click', t.step_func(function () { assert_equals(++i, 3) }), false);
-    button.onclick = t.step_func(function () { assert_equals(++i, 1); });
-    button.addEventListener('click', t.step_func(function () { assert_equals(++i, 4) }), false);
-    button.click()
-    assert_equals(button.getAttribute("onclick"), uncalled)
-    assert_equals(i, 4);
-    t.done()
-  });
-});
-primitives.forEach(function(primitive) {
-  var t = async_test("Event handler listeners should be registered when they " +
-                     "are first set to an object value (" +
-                     format_value(primitive) + ").");
-  t.step(function() {
-    var i = 0;
-    var uncalled = "t.step(function() { assert_unreached('First event handler.') })"
-    var button = document.createElement('button');
-    button.onclick = primitive;
-    assert_equals(button.onclick, null);
-    button.addEventListener('click', t.step_func(function () { assert_equals(++i, 1) }), false);
-    button.setAttribute('onclick', uncalled); // event handler listener is registered here
-    button.addEventListener('click', t.step_func(function () { assert_equals(++i, 3) }), false);
-    button.onclick = t.step_func(function () { assert_equals(++i, 2); });
-    button.addEventListener('click', t.step_func(function () { assert_equals(++i, 4) }), false);
-    button.click()
-    assert_equals(button.getAttribute("onclick"), uncalled)
-    assert_equals(i, 4);
-    t.done()
-  });
-});
-var t = async_test("Event handler listeners should be registered when they " +
-                   "are first set to an object value.");
-t.step(function() {
-  var i = 0;
-  var uncalled = "t.step(function() { assert_unreached('First event handler.') })"
-  var button = document.createElement('button');
-  button.addEventListener('click', t.step_func(function () { assert_equals(++i, 1) }), false);
-  button.setAttribute('onclick', uncalled); // event handler listener is registered here
-  button.addEventListener('click', t.step_func(function () { assert_equals(++i, 3) }), false);
-  button.onclick = t.step_func(function () { assert_equals(++i, 2); });
-  button.addEventListener('click', t.step_func(function () { assert_equals(++i, 4) }), false);
-  button.click()
-  assert_equals(button.getAttribute("onclick"), uncalled)
-  assert_equals(i, 4);
-  t.done()
-});
-</script>
diff --git a/testing/web-platform/tests/html/webappapis/scripting/events/event-handler-spec-example.window.js b/testing/web-platform/tests/html/webappapis/scripting/events/event-handler-spec-example.window.js
new file mode 100644
index 000000000000..7bfbe58bce55
--- /dev/null
+++ b/testing/web-platform/tests/html/webappapis/scripting/events/event-handler-spec-example.window.js
@@ -0,0 +1,51 @@
+var objects = [{}, function() {}, new Number(42), new String()];
+var primitives = [42, null, undefined, ""];
+objects.forEach(function(object) {
+  test(function() {
+    var i = 0;
+    var uncalled = "assert_unreached('First event handler.');"
+    var button = document.createElement('button');
+    button.onclick = object; // event handler listener is registered here
+    assert_equals(button.onclick, object);
+    button.addEventListener('click', function () { assert_equals(++i, 2) }, false);
+    button.setAttribute('onclick', uncalled);
+    button.addEventListener('click', function () { assert_equals(++i, 3) }, false);
+    button.onclick = function () { assert_equals(++i, 1); };
+    button.addEventListener('click', function () { assert_equals(++i, 4) }, false);
+    button.click()
+    assert_equals(button.getAttribute("onclick"), uncalled)
+    assert_equals(i, 4);
+  }, "Event handler listeners should be registered when they are first set to an object value " +
+     "(" + format_value(object) + ").");
+});
+primitives.forEach(function(primitive) {
+  test(function() {
+    var i = 0;
+    var uncalled = "assert_unreached('First event handler.');"
+    var button = document.createElement('button');
+    button.onclick = primitive;
+    assert_equals(button.onclick, null);
+    button.addEventListener('click', function () { assert_equals(++i, 1) }, false);
+    button.setAttribute('onclick', uncalled); // event handler listener is registered here
+    button.addEventListener('click', function () { assert_equals(++i, 3) }, false);
+    button.onclick = function () { assert_equals(++i, 2); };
+    button.addEventListener('click', function () { assert_equals(++i, 4) }, false);
+    button.click()
+    assert_equals(button.getAttribute("onclick"), uncalled)
+    assert_equals(i, 4);
+  }, "Event handler listeners should be registered when they are first set to an object value " +
+     "(" + format_value(primitive) + ").");
+});
+test(function() {
+  var i = 0;
+  var uncalled = "assert_unreached('First event handler.');"
+  var button = document.createElement('button');
+  button.addEventListener('click', function () { assert_equals(++i, 1) }, false);
+  button.setAttribute('onclick', uncalled); // event handler listener is registered here
+  button.addEventListener('click', function () { assert_equals(++i, 3) }, false);
+  button.onclick = function () { assert_equals(++i, 2); };
+  button.addEventListener('click', function () { assert_equals(++i, 4) }, false);
+  button.click()
+  assert_equals(button.getAttribute("onclick"), uncalled)
+  assert_equals(i, 4);
+}, "Event handler listeners should be registered when they are first set to an object value.");
diff --git a/testing/web-platform/tests/html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-late.html b/testing/web-platform/tests/html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-late.window.js
similarity index 64%
rename from testing/web-platform/tests/html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-late.html
rename to testing/web-platform/tests/html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-late.window.js
index 83ee25032c58..2892a4c3ab98 100644
--- a/testing/web-platform/tests/html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-late.html
+++ b/testing/web-platform/tests/html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-late.window.js
@@ -1,10 +1,3 @@
-<!doctype html>
-<meta charset="utf-8">
-<title>Invalid uncompiled raw handlers should only be compiled when about to call them.</title>
-<script src="/resources/testharness.js"></script>
-<script src="/resources/testharnessreport.js"></script>
-<body>
-<script>
 setup({ allow_uncaught_exception: true });
 
 test(function() {
@@ -20,6 +13,4 @@ test(function() {
   div.dispatchEvent(new Event("click"));
   assert_equals(div.onclick, null);
   assert_array_equals(events, ["click 1", "error", "click 2"]);
-});
-</script>
-</body>
+}, "Invalid uncompiled raw handlers should only be compiled when about to call them");
diff --git a/testing/web-platform/tests/html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-once.html b/testing/web-platform/tests/html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-once.window.js
similarity index 52%
rename from testing/web-platform/tests/html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-once.html
rename to testing/web-platform/tests/html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-once.window.js
index a67f66ead4ff..b39b54b0e9ce 100644
--- a/testing/web-platform/tests/html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-once.html
+++ b/testing/web-platform/tests/html/webappapis/scripting/events/invalid-uncompiled-raw-handler-compiled-once.window.js
@@ -1,10 +1,3 @@
-<!doctype html>
-<meta charset="utf-8">
-<title>Invalid uncompiled raw handlers should only be compiled once.</title>
-<script src="/resources/testharness.js"></script>
-<script src="/resources/testharnessreport.js"></script>
-<body>
-<script>
 setup({ allow_uncaught_exception: true });
 
 var errors = 0;
@@ -18,6 +11,4 @@ test(function() {
   assert_equals(e.onclick, null);
   assert_equals(e.onclick, null);
   assert_equals(errors, 1);
-});
-</script>
-</body>
+}, "Invalid uncompiled raw handlers should only be compiled once");
diff --git a/testing/web-platform/tests/html/webappapis/scripting/events/invalid-uncompiled-raw-handler-keeps-position.window.js b/testing/web-platform/tests/html/webappapis/scripting/events/invalid-uncompiled-raw-handler-keeps-position.window.js
new file mode 100644
index 000000000000..f9443bf99a0a
--- /dev/null
+++ b/testing/web-platform/tests/html/webappapis/scripting/events/invalid-uncompiled-raw-handler-keeps-position.window.js
@@ -0,0 +1,20 @@
+setup({ allow_uncaught_exception: true });
+
+test(function() {
+  var events = [];
+  window.onerror = function() {
+    events.push("error");
+  };
+
+  var div = document.createElement("div");
+  div.addEventListener("click", function (e) { events.push("click 1"); });
+  div.setAttribute("onclick", "}");
+  div.addEventListener("click", function (e) { events.push("click 3"); });
+  assert_equals(div.onclick, null);
+  assert_array_equals(events, ["error"]);
+
+  events = [];
+  div.onclick = function (e) { events.push("click 2"); };
+  div.dispatchEvent(new Event("click"));
+  assert_array_equals(events, ["click 1", "click 2", "click 3"]);
+}, "Compiling invalid uncompiled raw handlers should keep the position in event listener list");
diff --git a/testing/web-platform/tests/html/webappapis/scripting/events/resources/event-handler-body.js b/testing/web-platform/tests/html/webappapis/scripting/events/resources/event-handler-body.js
new file mode 100644
index 000000000000..656903cf99e6
--- /dev/null
+++ b/testing/web-platform/tests/html/webappapis/scripting/events/resources/event-handler-body.js
@@ -0,0 +1,26 @@
+const windowReflectingBodyElementEventHandlerSet =
+  new Set(['blur', 'error', 'focus', 'load', 'resize', 'scroll']);
+
+function handlersInInterface(mainIDL, name) {
+  return mainIDL.find(idl => idl.name === name).members.map(member => member.name.slice(2));
+}
+
+const handlersListPromise = fetch("/interfaces/html.idl").then(res => res.text()).then(htmlIDL => {
+  const parsedHTMLIDL = WebIDL2.parse(htmlIDL);
+  const windowEventHandlers = handlersInInterface(parsedHTMLIDL, "WindowEventHandlers");
+  const globalEventHandlers = handlersInInterface(parsedHTMLIDL, "GlobalEventHandlers");
+  const documentAndElementEventHandlers = handlersInInterface(parsedHTMLIDL, "DocumentAndElementEventHandlers");
+
+  const shadowedHandlers = [
+    ...windowReflectingBodyElementEventHandlerSet,
+    ...windowEventHandlers
+  ];
+  const notShadowedHandlers = [
+    ...globalEventHandlers.filter(name => !windowReflectingBodyElementEventHandlerSet.has(name)),
+    ...documentAndElementEventHandlers
+  ];
+  return {
+    shadowedHandlers,
+    notShadowedHandlers
+  };
+});