Run benchmarks on CI

Author: jridgewell

.github/workflows/test.yml

@@ -26,6 +26,12 @@ jobs:
         uses: actions/setup-node@v1
         with:
           node-version: ${{ matrix.node-version }}
-      - name: Test legacy node
+      - name: Test node
         run: |
           node dist/gen-mapping.umd.js
+      - name: Benchmark
+        run: |
+          npm run benchmark:install
+          npm run benchmark:only
+        env:
+          CI: true