Build the project before running tests

package.json

@@ -8,9 +8,9 @@
     "build": "microbundle -f iife",
     "dev": "run-all \"serve\" \" microbundle watch -f iife \"",
     "deploy": "npm run build",
-    "test-setup": "node test/setup/checkout-wpt.mjs",
     "test:wpt": "npm run test-setup && cd test && cd wpt && (python wpt run --headless -y --log-wptreport ../report/data.json --log-wptscreenshot=../report/screenshots.txt --log-html=../report/index.html --inject-script ../../dist/scroll-timeline.js firefox scroll-animations || true)",
     "test:simple": "npm run test-setup && cd test && cd wpt && python wpt serve --inject-script ../../dist/scroll-timeline.js",
+    "test-setup": "node test/setup/checkout-wpt.mjs && npm run build",
     "test:compare": "node test/summarize-json.mjs test/report/data.json > test/report/summary.txt && echo 'Comparing test results. If different and expected, patch the following diff to test/expected.txt:' && diff test/expected.txt test/report/summary.txt"
   },
   "repository": {