Split GitHub Actions.

.github/workflows/browserstack.yml

@@ -0,0 +1,40 @@
+name: BrowserStack
+on: [push]
+env:
+  CI: true
+  NODE: 12.x
+
+jobs:
+  browserstack:
+    runs-on: ubuntu-latest
+    if: github.repository == 'twbs/bootstrap'
+
+    steps:
+      - name: Clone repository
+        uses: actions/checkout@v2
+
+      - name: Set Node.js version
+        uses: actions/setup-node@v1
+        with:
+          node-version: "${{ env.NODE }}"
+
+      - name: Set up npm cache
+        uses: actions/cache@v2
+        with:
+          path: ~/.npm
+          key: ${{ runner.os }}-node-v${{ env.NODE }}-${{ hashFiles('package.json') }}-${{ hashFiles('package-lock.json') }}
+          restore-keys: |
+            ${{ runner.OS }}-node-v${{ env.NODE }}-${{ hashFiles('package.json') }}-${{ hashFiles('package-lock.json') }}
+            ${{ runner.OS }}-node-v${{ env.NODE }}-
+
+      - name: Install npm dependencies
+        run: npm ci
+
+      - name: Run dist
+        run: npm run dist
+
+      - name: Run BrowserStack tests
+        run: npm run js-test-cloud
+        env:
+          BROWSER_STACK_ACCESS_KEY: "${{ secrets.BROWSER_STACK_ACCESS_KEY }}"
+          BROWSER_STACK_USERNAME: "${{ secrets.BROWSER_STACK_USERNAME }}"