Replace babel with buble

package.json

@@ -11,8 +11,8 @@
   "scripts": {
     "bundle": "rollup -c",
     "bundle-tests": "rollup -c rollup.tests.js --format umd > build/tests.js",
-    "build": "babel --out-dir lib --quiet src",
-    "build-tests": "babel --out-dir build/test --ignore test/common --quiet test",
+    "build": "buble -o lib src",
+    "build-tests": "node -e \"require('fs-extra').ensureDirSync('build')\" && buble --yes dangerousTaggedTemplateString -o build/test test && node -e \"require('fs-extra').removeSync('build/test/common')\"",
     "changelog": "offline-github-changelog > CHANGELOG.md",
     "lint": "eslint . && prettier --check '**/*.js'",
     "test": "npm run test-node && npm run test-docs",
@@ -47,9 +47,7 @@
   "homepage": "https://github.com/unexpectedjs/unexpected-dom",
   "devDependencies": {
     "@rollup/plugin-multi-entry": "^3.0.0",
-    "babel-cli": "^6.26.0",
-    "babel-core": "^6.26.3",
-    "babel-preset-env": "^1.7.0",
+    "buble": "^0.19.8",
     "coveralls": "^3.0.2",
     "eslint": "^6.0.0",
     "eslint-config-prettier": "^6.0.0",
@@ -59,6 +57,7 @@
     "eslint-plugin-node": "^10.0.0",
     "eslint-plugin-promise": "^4.2.1",
     "eslint-plugin-standard": "^4.0.0",
+    "fs-extra": "^8.1.0",
     "gh-pages": "^2.0.1",
     "istanbul": "^0.4.5",
     "jsdom": "^15.2.0",