Run WPT sync nightly on GitHub Action

etc/ci/update-wpt-checkout

@@ -190,8 +190,12 @@ function main() {
         if [[ "${code}" == "255" ]]; then
             echo "No changes to sync."
             return 0
-        elif [[ "${code}" != "" ]]; then
+        fi
+
+        if [[ "${code}" != "" ]]; then
             return "${code}"
+        else
+            return 0
         fi
     fi
 

etc/ci/wpt-nightly-update.sh

@@ -0,0 +1,44 @@
+#!/usr/bin/env bash
+
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+set -o errexit
+set -o nounset
+set -o pipefail
+
+# Using an existing log file, update the expected test results and amend the
+# last commit with the new results.
+function unsafe_update_metadata() {
+    ./mach update-wpt "${1}" || return 1
+    # Hope that any test result changes from layout-2013 are
+    # also applicable to layout-2020.
+    ./mach update-wpt --layout-2020 "${1}" || return 2
+    # Ensure any new directories or ini files are included in these changes.
+    git add tests/wpt/metadata tests/wpt/metadata-layout-2020 \
+        tests/wpt/mozilla/meta || return 3
+    # Merge all changes with the existing commit.
+    git commit -a --amend --no-edit || return 3
+}
+
+function update_metadata() {
+    unsafe_update_metadata "${1}" || \
+        { code="${?}"; cleanup; return "${code}"; }
+}
+
+function main() {
+    for n in $(seq 1 "${MAX_CHUNK_ID}")
+    do
+        code=""
+        update_metadata "wpt${n}-logs-linux/test-wpt.${n}.log" || \
+            code="${?}"
+        if [[ "${code}" != "" ]]; then
+            return "${code}"
+        fi
+    done
+}
+
+# Ensure we clean up after ourselves if this script is interrupted.
+trap 'cleanup' SIGINT SIGTERM
+main