Roll wpt testharness

This rolls up to SHA fa8fd1e513f1e8151b79246a7e0ef3cf3d90a127

Change-Id: Idfbd212eb1280686541100f6b4941249c32e2a2b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2585684
Auto-Submit: Luke Z <lpz@chromium.org>
Commit-Queue: Robert Ma <robertma@chromium.org>
Reviewed-by: Robert Ma <robertma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#836647}

third_party/blink/web_tests/resources/testdriver.js

@@ -146,6 +146,24 @@
                                                       y: centerPoint[1]});
         },
 
+        /**
+         * Deletes all cookies.
+         *
+         * This matches the behaviour of the {@link
+         * https://w3c.github.io/webdriver/#delete-all-cookies|WebDriver
+         * Delete All Cookies command}.
+         *
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} fulfilled after cookies are deleted, or rejected in
+         *                    the cases the WebDriver command errors
+         */
+        delete_all_cookies: function(context=null) {
+            return window.test_driver_internal.delete_all_cookies(context);
+        },
+
         /**
          * Send keys to an element
          *
@@ -458,6 +476,10 @@
             });
         },
 
+        delete_all_cookies: function(context=null) {
+            return Promise.reject(new Error("unimplemented"));
+        },
+
         send_keys: function(element, keys) {
             if (this.in_automation) {
                 return Promise.reject(new Error('Not implemented'));