diff --git a/testing/web-platform/meta/MANIFEST.json b/testing/web-platform/meta/MANIFEST.json
index a260a796af54..f22b97931434 100644
--- a/testing/web-platform/meta/MANIFEST.json
+++ b/testing/web-platform/meta/MANIFEST.json
@@ -11359,6 +11359,12 @@
      {}
     ]
    ],
+   "fullscreen/api/promises-resolve-manual.html": [
+    [
+     "/fullscreen/api/promises-resolve-manual.html",
+     {}
+    ]
+   ],
    "fullscreen/model/move-to-fullscreen-iframe-manual.html": [
     [
      "/fullscreen/model/move-to-fullscreen-iframe-manual.html",
@@ -265976,6 +265982,11 @@
      {}
     ]
    ],
+   "css/tools/README.md": [
+    [
+     {}
+    ]
+   ],
    "css/tools/apiclient/.gitignore": [
     [
      {}
@@ -266036,51 +266047,6 @@
      {}
     ]
    ],
-   "css/tools/html2xhtml.py": [
-    [
-     {}
-    ]
-   ],
-   "css/tools/list-all.pl": [
-    [
-     {}
-    ]
-   ],
-   "css/tools/list-all.sh": [
-    [
-     {}
-    ]
-   ],
-   "css/tools/make-html.py": [
-    [
-     {}
-    ]
-   ],
-   "css/tools/supportprop.py": [
-    [
-     {}
-    ]
-   ],
-   "css/tools/templates/filename-list.tmpl": [
-    [
-     {}
-    ]
-   ],
-   "css/tools/travis/LICENSE": [
-    [
-     {}
-    ]
-   ],
-   "css/tools/travis/build.py": [
-    [
-     {}
-    ]
-   ],
-   "css/tools/travis/vcs.py": [
-    [
-     {}
-    ]
-   ],
    "css/tools/w3ctestlib/.hgignore": [
     [
      {}
@@ -330828,6 +330794,12 @@
      {}
     ]
    ],
+   "fullscreen/api/promises-reject.html": [
+    [
+     "/fullscreen/api/promises-reject.html",
+     {}
+    ]
+   ],
    "fullscreen/interfaces.html": [
     [
      "/fullscreen/interfaces.html",
@@ -398650,7 +398622,7 @@
    "support"
   ],
   "./.gitmodules": [
-   "525f7d93f00f11086aabc1f652cf06623e21986c",
+   "6a203e28d43909d7513daf8761281b351d2b2bd7",
    "support"
   ],
   "./.pyup.yml": [
@@ -489746,7 +489718,7 @@
    "reftest"
   ],
   "css/build-css-testsuites.sh": [
-   "0f1d955402449b61d134265ea5962d6ed93836f4",
+   "f08c6940dff13aad1b6c5fc81c08abcaa8aafc67",
    "support"
   ],
   "css/compositing/Blending_in_a_group_with_filter-ref.html": [
@@ -544589,6 +544561,10 @@
    "7301f0ec4d66b71a92818aa3d532c5eca718f677",
    "support"
   ],
+  "css/tools/README.md": [
+   "17dc12660a62726b5975e125cefb1cc42b007b6f",
+   "support"
+  ],
   "css/tools/apiclient/.gitignore": [
    "4f8c72d787595386529108512329027d424dad47",
    "support"
@@ -544637,42 +544613,6 @@
    "9dc0b6f869b328886b153eee2dd0b0053cd712e2",
    "support"
   ],
-  "css/tools/html2xhtml.py": [
-   "abaf4dec00fa3b29f556f35700410775acd63395",
-   "support"
-  ],
-  "css/tools/list-all.pl": [
-   "27670ddc5a347fa2d0608483875294f8f4957b07",
-   "support"
-  ],
-  "css/tools/list-all.sh": [
-   "040b805bb924cd18077cc07f7a449067d7fc0cd7",
-   "support"
-  ],
-  "css/tools/make-html.py": [
-   "3fb558bb57627987e143d415d8677508a2dfbaf2",
-   "support"
-  ],
-  "css/tools/supportprop.py": [
-   "92973da4c183e497ef7b4a888ca929216073f9ea",
-   "support"
-  ],
-  "css/tools/templates/filename-list.tmpl": [
-   "ddcb87e03b20a95d9b10ad00bbb1228e3fd5a9ba",
-   "support"
-  ],
-  "css/tools/travis/LICENSE": [
-   "0ea78bfe20b327310471cc22618f7c921c6e0481",
-   "support"
-  ],
-  "css/tools/travis/build.py": [
-   "470c482e0463459a3d0b48af0107a2429a281db8",
-   "support"
-  ],
-  "css/tools/travis/vcs.py": [
-   "715959f81edaae4a2ac5ad6a16dbb045c199074f",
-   "support"
-  ],
   "css/tools/w3ctestlib/.hgignore": [
    "68a4744eda8cfd5d6313a91e1468cffacf37b61f",
    "support"
@@ -544694,7 +544634,7 @@
    "support"
   ],
   "css/tools/w3ctestlib/Sources.py": [
-   "36436dff53c614783778a373223c07be4f70fc1d",
+   "1541268bf0bec6fcbf1c9e5ce60c31878f29314e",
    "support"
   ],
   "css/tools/w3ctestlib/Suite.py": [
@@ -544750,7 +544690,7 @@
    "support"
   ],
   "css/tools/w3ctestlib/templates/index.content.tmpl": [
-   "c9195c8e9ed930d37c3a64f65c0b43f1cb3d6fc0",
+   "cf6c10649767fbd6cd52672b14f1176537499c44",
    "support"
   ],
   "css/tools/w3ctestlib/templates/index.htm.tmpl": [
@@ -560686,7 +560626,7 @@
    "manual"
   ],
   "fullscreen/api/document-onfullscreenerror.html": [
-   "ed8836f302fffdaa407bf9bf7799effa17fb6823",
+   "1dd69713aaa8030892e68cfb0fec2fccb8863723",
    "testharness"
   ],
   "fullscreen/api/element-ready-check-allowed-cross-origin-manual.sub.html": [
@@ -560758,7 +560698,7 @@
    "manual"
   ],
   "fullscreen/api/element-request-fullscreen-not-allowed.html": [
-   "8991e8df530fa7c24a9e084f2ab17fa9c70fb120",
+   "5eac634c56810200d4c6a8b1c3c6f547ba1e7dc9",
    "testharness"
   ],
   "fullscreen/api/element-request-fullscreen-null-ns-manual.html": [
@@ -560778,7 +560718,7 @@
    "manual"
   ],
   "fullscreen/api/element-request-fullscreen-timing-manual.html": [
-   "4ecd76a2ef773172d45f656f52a7358be2a4568d",
+   "48df66c401edcba47d1336313833a24d5e3d211d",
    "manual"
   ],
   "fullscreen/api/element-request-fullscreen-top-manual.html": [
@@ -560801,6 +560741,14 @@
    "9d9bec938f185b2461da4d00a5683ad5d07ee577",
    "testharness"
   ],
+  "fullscreen/api/promises-reject.html": [
+   "2bc121b4bc0a397f2f25c5fca1aa32fa8727b776",
+   "testharness"
+  ],
+  "fullscreen/api/promises-resolve-manual.html": [
+   "ec9276eb2b2ab279a84aa06a644b4333e46e970d",
+   "manual"
+  ],
   "fullscreen/api/resources/attempt-fullscreen.html": [
    "33e277b3f06677f14eed442ecce76b408e7e006e",
    "support"
@@ -560858,7 +560806,7 @@
    "manual"
   ],
   "fullscreen/trusted-click.js": [
-   "e401e8e8bcd97446991398d6021a9bd712c923c5",
+   "069f4d40fbcb4e933d4f651d3220820836615660",
    "support"
   ],
   "gamepad/OWNERS": [
diff --git a/testing/web-platform/tests/fullscreen/api/document-onfullscreenerror.html b/testing/web-platform/tests/fullscreen/api/document-onfullscreenerror.html
index 499e77d0b99e..02cb94820fb0 100644
--- a/testing/web-platform/tests/fullscreen/api/document-onfullscreenerror.html
+++ b/testing/web-platform/tests/fullscreen/api/document-onfullscreenerror.html
@@ -7,12 +7,23 @@
 async_test(function(t)
 {
     var sync = true;
+    var promise_executed = false;
     assert_equals(document.onfullscreenerror, null, "initial onfullscreenerror");
     document.onfullscreenerror = t.step_func_done(function(event) {
+        assert_true(promise_executed);
         assert_false(sync);
     });
     var e = document.createElement('span');
-    e.requestFullscreen();
+    var promise = e.requestFullscreen();
+    if (promise) {
+        promise.catch(()=> {
+            assert_false(sync);
+            promise_executed = true;
+        });
+    } else {
+        // If promises aren't supported just treat it as already done.
+        promise_executed = true;
+    }
     sync = false;
 });
 </script>
diff --git a/testing/web-platform/tests/fullscreen/api/element-request-fullscreen-not-allowed.html b/testing/web-platform/tests/fullscreen/api/element-request-fullscreen-not-allowed.html
index eb9e23b85f94..3170c184823d 100644
--- a/testing/web-platform/tests/fullscreen/api/element-request-fullscreen-not-allowed.html
+++ b/testing/web-platform/tests/fullscreen/api/element-request-fullscreen-not-allowed.html
@@ -6,14 +6,24 @@
 <script>
 async_test(t => {
   const div = document.querySelector("div");
+  var promise_executed = false;
 
   document.addEventListener("fullscreenerror", t.step_func_done(event => {
     assert_equals(event.target, div, "event.target");
     assert_true(event.bubbles, "event.bubbles");
     assert_false(event.cancelable, "event.cancelable");
     assert_true(event.composed, "event.composed");
+    assert_true(promise_executed, "promise executed");
   }));
 
-  div.requestFullscreen();
+  var promise = div.requestFullscreen();
+  if (promise) {
+    promise.catch(()=> {
+      promise_executed = true;
+    });
+  } else {
+    // If promises aren't supported just treat it as already done.
+    promise_executed = true;
+  }
 });
 </script>
diff --git a/testing/web-platform/tests/fullscreen/api/element-request-fullscreen-timing-manual.html b/testing/web-platform/tests/fullscreen/api/element-request-fullscreen-timing-manual.html
index 1ccfc7a3fe44..359b688b4272 100644
--- a/testing/web-platform/tests/fullscreen/api/element-request-fullscreen-timing-manual.html
+++ b/testing/web-platform/tests/fullscreen/api/element-request-fullscreen-timing-manual.html
@@ -28,11 +28,19 @@ async_test(t => {
 }, 'Timing of fullscreenchange and resize events');
 
 async_test(t => {
-  document.createElement('a').requestFullscreen();
+  var promise = document.createElement('a').requestFullscreen();
+  var promise_executed = false;
+  if (promise) {
+    promise.catch(()=>{promise_executed = true; });
+  } else {
+    // if promises aren't supported treat it as executed.
+    promise_executed = true;
+  }
 
   // If fullscreenerror is an animation frame event, then animation frame
   // callbacks should be run after it is fired, before the timer callback.
   document.onfullscreenerror = t.step_func(() => {
+    assert_true(promise_executed, "promise executed");
     step_timeout(t.unreached_func('timer callback'));
     requestAnimationFrame(t.step_func_done());
   });
diff --git a/testing/web-platform/tests/fullscreen/api/promises-reject.html b/testing/web-platform/tests/fullscreen/api/promises-reject.html
new file mode 100644
index 000000000000..2f47d4cdcd06
--- /dev/null
+++ b/testing/web-platform/tests/fullscreen/api/promises-reject.html
@@ -0,0 +1,17 @@
+<!DOCTYPE html>
+<title>Promises#reject</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function(t)
+{
+    var e = document.createElement('span');
+    e.requestFullscreen().catch(t.step_func_done());
+});
+async_test(function(t)
+{
+    var e = document.createElement('span');
+    document.exitFullscreen().catch(t.step_func_done());
+});
+</script>
diff --git a/testing/web-platform/tests/fullscreen/api/promises-resolve-manual.html b/testing/web-platform/tests/fullscreen/api/promises-resolve-manual.html
new file mode 100644
index 000000000000..e58b8d90fed4
--- /dev/null
+++ b/testing/web-platform/tests/fullscreen/api/promises-resolve-manual.html
@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<title>Promises#resolve</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="../trusted-click.js"></script>
+<div id="log"></div>
+<script>
+async_test(function(t)
+{
+    var div = document.querySelector("div");
+    trusted_request_with_promise(t, div, document.body,
+    () => {
+        assert_equals(document.fullscreenElement, div, "fullscreenElement before exitFullscreen()");
+        document.exitFullscreen().then(()=> {
+          assert_equals(document.fullscreenElement, null, "fullscreenElement after exiting fullscreen");
+          t.done();
+        });
+        assert_equals(document.fullscreenElement, div, "fullscreenElement after exitFullscreen()");
+    }, t.unreached_func("Request fullscreen failed"));
+});
+</script>
diff --git a/testing/web-platform/tests/fullscreen/trusted-click.js b/testing/web-platform/tests/fullscreen/trusted-click.js
index cab23e35f9c8..7ee0669eece3 100644
--- a/testing/web-platform/tests/fullscreen/trusted-click.js
+++ b/testing/web-platform/tests/fullscreen/trusted-click.js
@@ -19,5 +19,20 @@ function trusted_click(test, callback, container)
 // Invokes element.requestFullscreen() from a trusted click.
 function trusted_request(test, element, container)
 {
-    trusted_click(test, () => element.requestFullscreen(), container || element.parentNode);
+    trusted_click(test, () => {
+        var promise = element.requestFullscreen();
+        if (promise) {
+            // Keep the promise resolution silent. Otherwise unhandledrejection
+            // may fire for the failure test cases.
+            promise.then(() => {}, () => {});
+        }
+    }, container || element.parentNode);
+}
+
+// Invokes element.requestFullscreen() from a trusted click.
+function trusted_request_with_promise(test, element, container, resolve, reject)
+{
+    trusted_click(test, () => {
+        element.requestFullscreen().then(resolve, reject);
+    }, container || element.parentNode);
 }