Import WPT tests every week instead of every day

We often have multiple imports stacked up which makes it more confusing
to land each one. In addition, giving a week to do the import will give
us more margin to triage failing tests and hopefully to be able to use
intermittent expectations for flaky tests.

.github/workflows/scheduled-wpt-import.yml

@@ -0,0 +1,87 @@
+name: Scheduled WPT import
+
+on:
+  schedule:
+    # Run this job every Sunday at 00:00.
+    - cron: "0 0 * * 0"
+
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+jobs:
+  linux:
+    # This job is only useful when run on upstream servo.
+    if: github.repository == 'servo/servo' || github.event_name == 'workflow_dispatch'
+    name: Linux
+    uses: ./.github/workflows/linux.yml
+    with:
+      layout: '2013'
+      wpt: 'sync'
+      unit-tests: false
+
+  linux-layout-2020:
+    # This job is only useful when run on upstream servo.
+    if: github.repository == 'servo/servo' || github.event_name == 'workflow_dispatch'
+    name: Linux (layout-2020)
+    uses: ./.github/workflows/linux.yml
+    with:
+      layout: '2020'
+      wpt: 'sync'
+      unit-tests: false
+
+  sync:
+    # This job is only useful when run on upstream servo.
+    if: github.repository == 'servo/servo' || github.event_name == 'workflow_dispatch'
+    name: Synchronize WPT Nightly
+    runs-on: ubuntu-latest
+    needs:
+      - "linux"
+      - "linux-layout-2020"
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+        with:
+          fetch-depth: 2
+      # Download all artifacts
+      - uses: actions/download-artifact@v3
+      - name: Prep environment
+        run: |
+          python3 -m pip install --upgrade pip virtualenv
+          sudo apt update
+          python3 ./mach bootstrap
+      - name: Add upstream remote
+        run: |
+          git config --local user.email "josh+wptsync@joshmatthews.net"
+          git config --local user.name "WPT Sync Bot"
+          git remote add upstream https://github.com/servo/servo.git
+          git fetch --unshallow upstream
+      - name: Fetch upstream changes before syncing
+        run: |
+          ./etc/ci/update-wpt-checkout fetch-upstream-changes
+      - name: Run WPT Update
+        env:
+          MAX_CHUNK_ID: 20
+          WPT_SYNC_TOKEN: ${{ secrets.WPT_SYNC_TOKEN }}
+        run: |
+          export CURRENT_DATE=$(date +"%d-%m-%Y")
+          echo $CURRENT_DATE
+          echo "CURRENT_DATE=$CURRENT_DATE" >> $GITHUB_ENV
+          ./etc/ci/wpt-scheduled-update.sh
+      - name: Push changes
+        uses: ad-m/github-push-action@master
+        with:
+          branch: wpt_update_${{ env.CURRENT_DATE }}
+      - name: Open PR
+        env:
+          GH_TOKEN: ${{ secrets.WPT_SYNC_TOKEN }}
+          UPDATE_BRANCH: wpt_update_${{ env.CURRENT_DATE }}
+        run: |
+          BODY=$(cat <<EOF
+          Automated downstream sync of changes from upstream as of ${{ env.CURRENT_DATE }}
+          [no-wpt-sync]
+          r? @servo-wpt-sync
+          EOF
+          )
+          gh pr create \
+            --title "Sync WPT with upstream (${{ env.CURRENT_DATE }})" \
+            --body "$BODY" --head ${{ env.UPDATE_BRANCH }} | xargs gh pr comment $1 --body "@bors-servo r+"